My stats did not change at all. I added some more clinical experiences but that's about it. I also redid my entire AMCAS. IMHO I think the biggest difference was my interview.
I think interview is the biggest part too. Looking back, although my stats were lower last year, I had the chance to prove myself at the interview and just didn't do so. This year, with higher stats, it helped with getting more interviews, but the way I approached the interviews were different as well.