Hi...I had to reapply this year. I luckily just got my first acceptance a few days ago.
1) Wait. Take a bit of a deep breath. Nothing I can tell you here is going to cure the pain of being rejected from med school--it's a sucky sucky process, but I promise you, you'll be fine...the "uncertainty about the future" is by far the worst feeling but I can guarantee life will move on and you will land on your feet.
2) I'm unsure when it's apropo to start doing this (ask a premed advisor or call the actual med schools and ask them when it would be appropriate) but call the schools from which you were rejected and ask for an in-person (if the school is close) or over-the-phone meeting to discuss how you weren't accepted this past season and would like to get some specific feedback as to how you can make your application more competitive in order to get that interview or to get that post-interview acceptance. This is a vital step. I didn't do this last year, and was reaaallllyyyy reaaallllyyy kicking myself around January that because I hadn't done it I had blown an entire year.
3) React. If GPA or MCAT are the concern, a post-bacc program or SMP is really the best option despite cost. If it's lack of clinical experience...get a fulltime job for your year off doing clinical experience. If it's lack of research, get a job doing research. No matter what, you should come out of that conversation with some specific objectives to check off for the school. Don't sulk. Don't be lazy. Getting the perfect job required me to apply to over 100 of them. Icing on the cake would be to continue buffing up your EC's with volunteer experience and other activities.
4) Work on your interview skills and essay writing skills
--Begin tangent: I will interject, here, though, that I believe that these two are highly overrated. People come on here bemoaning that "I blew the interview! I have no chance of acceptance!" And then end up accepted. The interview and your essays are just two parts of your application and IMO small ones at that. They're really things that you really "don't screw up" rather than "impress." After two years in this process I'm strongly of the opinion that GPA and MCAT are god and everything else is either just a requisite filled or icing on the cake. (Edit: I exaggerated a little here--you should still write a knockout essay and have excellent interviewing skills, but my point is that I'd argue most people have good essays and with practice most people get excellent at interviewing).
--End Tangent
This is probably the most annoying thing about reapplying--you've got to completely rewrite everything. Everything. No personal statement or secondary question should be repeated. Activity descriptions should at the bare minimum be edited. As for interviewing, I actually found that my parents were a great source to bounce interview questions off of--or at least the general ones about your strengths weaknesses, etc etc. Of course, this depends on your parents...and it was convenient because I'm living with them while working this year.
If you've got the money you might also look into hiring a consultant. If I had to apply a 3rd time I would've done this.