I did CH last year, declined my offers, and re-applied this year. I got some feedback on my application and it had more to do with "fit" than actual "holes" in my application.
I pretty much continued what I was doing (added 2 more presentations, 2 TA'd classes, a year more of clinical experience, etc). I spent A LOT more time reviewing my essays and working on my app. Your essays are REALLY REALLY important, as some DCT's I talked to said this was one area where they tried to get a "feel" of the applicant...as most have similar stats.