Just so you know, I'm in the same boat. I'm kinda gutted as I just spent the best part of 3 days getting 100% on every level. After a short rage I just decided to start over. It seems that when you chapter select and you complete an act, your save is then overwritten from when you last saved. In my case it was the last stage and I'm guessing you too. I recommend getting 100% on each act from the start (without chapter select) and continue until the end. If you don't get the percentage, just press the guide button and dashboard before it autosaves and load up your game and it will start you off at the beginning of that act.
Last edited by Evrae; 01-12-2013 at 10:04 AM.