If the school doesn't limit the number of applications you can submit than there really isn't a set number of times. I'd say if you can realize why you weren't accepted the first time around and fix it you should be fine.
For instance, I applied last cycle. Had 2 interviews and no acceptances. Improved my MCAT from a 30 to a 34. Applied (primaries and secondaries) by mid August instead of late October. Worked at 2 different volunteer positions since last September (that I couldn't list on my primary b/c I hadn't started them yet) and got a job teaching kids with learning and behavioral disabilities. So far this cycle have 5 interviews and one rejection so far.
If you are reapplying without trying to improve your application then you probably won't have any luck. Also I'd recommend not reusing secondary essays. The schools keep your apps from previous years (or at least say they do) and might not be representative of you as an applicant anymore.