Formal:
* Paroled
* Pardoned
* Commuted
* Granted clemency
* Spared
* Exempted
Informal:
* Let off the hook
* Given a break
* Saved
* Rescued
* Released
Other possibilities:
* Postponed (if referring to a punishment)
* Delayed (if referring to a sentence)
* Deferred (if referring to a decision)
The best synonym for "reprieved" will depend on the specific situation and the desired level of formality.