How much crystal, of what type and how big was the batch?
You are currently at roughly 66% attenuation. Lager yeasts like to get up into the 70's and even 80% range. I think the key question is whether the lager yeast really is truly finished. They can go on for a long time, slowly chomping away, but once they finish, there are no ale yeasts that will dry it out any more than it already is. (As it is, lager yeasts can ferment maltotriose, which ale yeasts cannot.)
If it's really a LOT of crystal that was added, then you have too many dextrins causing the sweetness, and maybe the only thing that might dry it out is to go funky. Again, that's assuming the lager strain finished.
If there was a more moderate amount of crystal, then I'd say it may need more time lagering and it may fix itself.
I'd either just throw it in the back of the kegerator and forget about it for a year, go for blending it, or funkify it. "I'll B-Rett Bock" might be a cool name for something like that.

Oh, for future batches, Traditional Bock really shouldn't have any crystal/caramel/caramunich in it. It should be all about melanoidan development, not caramel development. Any carmamel notes should be residual from the (traditional) decoction process (if any), not from caramel malts.
HTH-