My opponent pegged for getting to 31 by playing a jack. If I play a jack after that, do I peg for the doubles?
According to the rules of cribbage:
Card combinations cannot span a reset; once the total reaches 31 (or a Go has been scored) and counting has re-started at zero, cards already played cannot contribute to runs or pairs.
No - cards from one round of play cannot be combined with cards from the next.
The player who called Go leads for the next series of plays, with the count starting at zero. The lead may not be combined with any cards previously played to form a scoring combination; the Go has interrupted the sequence.