You can also try creating that track by instrument rather than Style with a new session of BIAB.
Save your current project. Here after, I'll call this the Main Project.
Create a New Project. Use the same Style, tempo and Key signature as your Main Project.
Populate at least the first 4 bars with the chord progression of your Main Project you want the 16 bars to be the same as the first 4 bars in the saved project. A tip is to also make the next Bar past the last Bar of the chord progression you're creating the same as your first Bar so the progression will generate to voice the correct first chord in a repeat. If your chord progression happens to not be a repetition of the first four chords, populate this project by matching the Chord Chart of your Main Project.
Populate the 6 mixer tracks with the RealTrack you want to use in your Main Project. (Exempt Drums by muting the track.)
Render the song.
Theoretically, this should generate each track in a similar pattern in the first 4 bars to what you are wanting for your Main Project.
Each should be a bit different, but correct in the pattern so you can use selections from each rendered mixer channel to create a more live feel of your song than just a 4 bar repeating pattern of a single track.
If a particular channel generates a pattern too dissimilar to what you're looking for, you can regenerate that individual track until in comes back around to generating the pattern you want.
Listen to each track and decide which mixer channel track you want to use for each 4 bar section of your 16 bars in your Main Project. You only need 4 channel tracks to complete individual sections of 16 Bars and you have 6 to choose from.
Freeze and export each of the 4 channels you've selected to use in your main project being sure to give each exported track a unique name to identify the individual files bar placement in your Main Project. For example - First Group, Second Group, Third Group or similar.
Save and close this BIAB session and reopen your Main Project.
BIAB allows you to import audio and select the bar to place the audio anywhere in your song project while also choosing to merge the audio rather than overwrite any existing audio. Choose to overwrite any existing audio when the Import Window appears. This will allow the repeat to enter the track properly.
Import each of the saved audio snippets you've created in the order where you've decided to place them into this song. This should merge all four of the snippets into one Audio Track for the first 16 bars of your song. For instance place First Group at Bar 1-1-1; Second Group at Bar 1-5-1 and so on.
Make this Audio Track to a Performance Track and save your project. This should give you a more realistic performance and live feel more so than using just a 4 bar repetition of a single rendered track. Take advantage of these being 'Real' tracks.
Another thing I find useful when building a song by Instrument rather that Style is to use the BIAB StylePicker to locate and audition instruments rather than the ReaTrack Picker. There are several benefits to doing this.
The BIAB Stylepicker allows you to hear and audition a Style using the actual Chord Chart of your current project. You can choose to hear it play the whole song or the first 4 bars of the song in order to audition many Styles very quickly. The RealBand Stylepicker does not have this feature. It is important to note here that a Style's Demo can sound considerably different than that Style will play over your specific chord progression, Key and tempo. This is key to finding the right RealTrack for your particular song.
Since Styles can contain as many as 5 or more instruments, you will also audition hundreds of different instruments in minutes. Many times I have come across an instrument that perfectly fits into my specific song that I had not previously considered but hearing it play over my Chord Chart, works wonderfully.
Another way using the Stylpicker helps is to search by PGMusic Session Artist. This really takes advantage of the 'Realness' of RealTracks in a way that no other format such as loops and samples can match. This method gives you the perception of really having a live musician at your session. You have the same musician at your session playing different instruments (perhaps acoustic guitar, electric guitar, nylon guitar), playing the exact same instrument using different patterns (having 4 or 6 A/B part markers rather than two), strumming, fingerpicking, slide. I also find instruments playing a complementary pattern between two instruments (a strumming guitar and fingered guitar from the same Style that are made to be used together) - These are very powerful features that one would otherwise find only if they stumble across that particular Style to use it in their song project.
I did a RealTrack StylePicker search for PGMusic Session Musician Andy Reiss on a project that was 4/4, sw8, at 110 tempo. Using the StylePicker to search filtered for Reiss, 4/4, sw8 and not including a tempo, returned 45 Styles I could audition Andy Reiss playing over my specific Chord Chart. Not every instance will work, but there is a lot of opportunity that would have otherwise been missed.
One way I use this feature a lot is in a song where perhaps I have an 8 bar Lead Guitar Solo and my song also uses an electric Rhythm Guitar track. If a complementary Rhythm Guitar is used in the Style I found the Lead Guitar in my StylePicker search and it's suitable to play over my specific Chord Chart, I will also insert the complementary electric Rhythm Guitar from that Style into the 8 Bar solo spot which adds variety, interest and change to my song making it more unique. Remember, each Channel Track can have up to ten instrument changes inserted. This method works quite often and works similarly to a Part Marker change. Sometimes you will find two instruments, perhaps a Sax and lead Guitar that play off each other back and forth like two live musicians may do when playing together.
Using the StylePicker this way also works wonderfully well with MIDI......
Just some thoughts that may help you spice up your tracks a bit.