My ex girlfriend has stopped initiating contact but continues to answer my texts and calls?

There are definitely some feelings attached for sure, and I think personally you need to do something about it. You either confront her headon or you leave it alone, she might not let it go to far without being somewhat relentless towards you, but you will have to talk to her to find that out. If you feel the same about her then you two need to work it out and get everything out on table once and for all.