If he can recapture the magic, and you see recruiting get back to where it was before the investigation, I give him an extension. That said, I would also make sure that said extension has a very Institution favorable buyout clause, in case something happens. I would also have my short list of candidates ready at all times(Which any AD should have anyway), in case it was more of a last hurrah. It's a tough situation, because L has proven himself to be a good soldier and leader, but you've also hit that rough patch.
College Basketball coaches are older on average than their football counterparts, so there's that, but I would also want to start planning on a succession strategy.