This is handled on a case by case, completely dependent on the circumstances. We've had one paladin be rebuilt and only allowed to keep five levels of paladin and then the rest were replaced by fighter levels (with no allowance for stat changes) for going directly against the god's dogma. We've had a cleric who fell but was scooped up by another deity nearly immediately (quest related) who was simply rebuilt with the proper domains. We've had still others that 'fell' but it was a more serene circumstance, loosing sight of their 'calling' and finding that family was more important at that time. We have had temporary 'falls' where all stayed the same and the individuals were limited in what they could call upon but eventually earned all back...
It is very much a relational situation, highly dependent upon the circumstances. The bottom line, however, is we strive to make the mechanics fit the RP at all times on these matters.
~row
