Never ever ever re-use essays. If you are reapplying they will definitely skim over your old essays and that's a huge "not enough effort" strike against you.
It sucks because there are only so many ways to say why you want to be a doctor, but it helps to mention the NEW things you've been doing and how they've taught and/or inspired you.
And yes, I am feeling pretty discouraged myself... it's my second app, the admissions director at one school recommended that I take 32 hours worth of graduate chem/bio courses, and I'm listening to him even though the prevailing opinion on here is that this is a bad idea. I have 24 hours of 4.0 semesters and I'm pretty sure I am finishing 9 more (6 hours of which are freakin' physical chemistry classes!), along with 8 hours a week of great clinical experience as a nurse/pharmacist/PA/whatever needs doing at a free clinic for the homeless.
But... no interview yet. I applied to a few other places but I don't really expect to get in; I have a 32 MCAT (well above average for my target school), 3.3 science GPA, but 2.85 overall due to some bad semesters as an engineering major at a top five tech school. So, I pretty much have all my eggs in one basket.
I still have plenty of time for this cycle, especially given that this is a notoriously slow-moving med school, but it's a very bad helpless feeling to be working harder than ever (and finally being at the top of my classes) knowing that the only recognition I'm gonna get is if/when I finally get accepted, and I really can't control that.
Then again... it beats busing tables.