videotrack is right - you can do it with midi. but are the chords all on the same instrument like a piano? or are they on lots of instruments? either way it could be tedious. open the editable notation of the track you want to extend the notes on and you can extend the duration of individual notes but its a bit tedious if you have to do it for a complete song. look up the process in the manual. then freeze the track after you've edited the notes. but bear in mind some instruments like an organ can hold a note but others like a guitar can't as the note dies away after being plucked.

personally i'd do it in RealBand as you can do it once and then cut and paste the edited part overwriting the original so it's the same for all the repeats.