With some of the nice quality sphagnum it will come back given good quality light we normally use in terrariums. I actually have to microwave the stuff I would get from black jungle because it always came back and tended to smother some of my micro plants! That aside, it was fun when it came back in frog tanks, and it adapted well.
I've had really poor luck with live sphagnum growing in a frog tank, but it's likely the change in conditions - particularly light. Around here it's usually found in partial to full sun. I sun dried some and had it go dormant and come back later with some sundews I planted in it and it did much better. Key seems to start with good quality dry, forget about it, and then it grows!