I just frag em, attach them to a rock with wedding veil & rubberbands until they attach. New ones usually grow back from where I cut the old ones from anyway.
I know a couple of people who (cringe) just toss a couple of the mushrooms in a blender with some tank water, coarse blend them, then pour the whole thing back in the tank.

They get about a 90% re-growth rate from all the small pieces from the slurry. I've never done it, seems a bit brutal to me, not to mention the mess & potential for chemical spikes, but they have had great luck with it, and do it frequently.