Q: If you draw a Creeper with Wormhole, you play it and then redraw. What if you draw yet another Creeper?

A: You keep drawing until you get a non-Creeper. Of course, this also applies to:

Analogues of Wormhole (found in Star Fluxx) include (some with slight variations such as conditional requirements for use):
Magic Shoes in Oz Fluxx
Egads! in Batman Fluxx
Magic Portal in Adventure Time Fluxx
Time Doorway in Regular Show Fluxx
Shiny! in Firefly Fluxx
Great Idea! in Stoner Fluxx

the following have a Wormhole analogue, but do not have Creepers naturally occurring in the deck:
Mystery Play in Fluxx 5.0 and SE
Open The Door in Monster Fluxx
Chemical X in Cartoon Network Fluxx