That is the cycle,, the pitcher is done,, you'll get more,, Provide plenty of humidity,, you can also go to the pet store and buy baby crickets, to feed the pitchers,, Use tweezers to make sure the crickets go IN the pitchers.
BTW CUT off the dying pitchers to promote growth and send energy to new growth. I had pitchers for a few years, and learned alot,, they don't like sudden change in humidity and like 73-77 degrees. Nothing is wrong with your plant, it's like a bloom that is now dying and will set new pitchers especially this spring
and Summer,, No worries