[Clipper]

Another player would need to be taking it off the Wizard in-between too. The Munchkinomicon only gives you a Spell when you get it off somebody else, and at the start of your turn if you have it. If you already have it, you can't sacrifice cards nor a level to get another Spell.

If somebody else was also sacrificing cards/levels, you would be able to gather enough Spell cards to use the Wizard's Charm Spell again, I guess.