Leaf pulls off Dionaea are relatively easy... I've had decent success with striking them this past season.
http://www.carnivorousplants.org/grow/p ... afPullings
If you are repotting the plant, you'll want to tug a leaf off with the white portion (rhizome) still intact. A clean removal as opposed to the leaf snapping off - commonly referred to as a cutting, often done successfully with Drosera. I don't believe cuttings work well with Dionaea. I've also managed to pull off roots with the pulling this way, I planted the entire piece and sprouted up a plantlet after some time, roughly a few months, in the same pot as mother plant.
If the plant is still nestled in its' pot, you can still take a pulling, though it takes a bit more work. I've been able to do it with a plant whose rhizome is slightly above the top soil. This way, I am able to remove a single leaf cleanly from green trap to white rhizome.