Tyler,
That's correct, as an officer you have only one opportunity to pass BUD/S. You can get medical roll-backs, but if you DOR or simply do not make times or pass certain evolutions...you're DONE. However, if enlisted you can essentailly fail or quit, serve a tour in the fleet, and then apply for another BUD/S date.
With that being said, BUD/S slots are incredibly hard to achieve as an Officer, even more so than pilot slots.
You can elist with a SEAL Challenge contract that guarantees you a BUD/S class upon completing RT and your "A" school* on the stipulation that you pass the SEAL Challenge sometime during RT:
500m swim, 12:00min
2 min sit-up
2 min push
max push
1.5 mi run, 11:30
(two min interval)
This or something very similar. You do that and your guaranteed a BUD/S class. A good college buddy of mine began recruit training last August (even without SEAL Challenge in his contract enlisment), is going to be done with "A" school in one week (Hospital Corpsman), and has an April BUD/S date with class 251. Exciting!
Those are the bones of it as far as I know. Any local Recruiter can get you squared away...just make sure you don't sign anything right off. These people are not like Officer Recruiters...
Also, check out "The Warrior Elite" by Dick Couch. Great book on the BUD/S experience.
*Oh yeah, SEAL hopefulls have only a selected list of jobs to chose from.