I have heard of waxing, anti-freeze, alcohol, and glycerine ways to treat and preserve plant materials, but I have never tried them before. You could also just place it in a bag of water and freeze it, but you would have to keep it in the freezer forever that way.

Type in "preserving plant materials" and you will get a list of sites explaining many different ways to do this.

drying methods/pressing probably won't preserve the pitcher well enough so that it can retain it's structure

there's a neat way to skeletonize a leaf, though i'm sure it's much for difficult to skeletonize a pitcher
http://edis.ifas.ufl.edu/BODY_EP004