Yes... you can enter chords as it's playing back but like has been mentioned, the time line keeps moving on.

I often will make changes as I see things that need changing in the song...

Yes, you must restart to make the changes active in the song.

IMHO, the best way is to simply stop the playback, make the changes, and then preview them to be sure they're correct.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.