By cutting off pitchers, do you mean brown or green tissue?
Brown, dead stuff should be trimmed off as it appears all year round.
If you're cutting off green stuff, you are removing material the plant wants to photosynthesise with. However, sarracenia benefit from burns, so a plant won't suffer if it's trimmed back completely every couple of years. If you trim it back every spring though, a weaker plant may grumble and never be able to perform at its best.
It's a balancing act. I trimmed all mine back this spring, but will be leaving everything green on next spring.