It would be fastest to take clones from them to start over rather than waiting for the whole plants to recover. It is going to be a slow recovery, by the time they're back full swing a new clone would have surpassed it. Or a bagseed planted now might even pass it by...
Added: I should have at least added a couple possible options to speed recovery... Sorry. You should add hydrogen peroxide to your water until the roots aren't brown any more. I don't recall the levels, check with the guys in the hydro section they have to do that more often than a dirt farmer like me.
Another option is to use bugs that eat dead plant material as odd as this will sound fungus gnats might speed it up and then kill them when they're done. I have never ever tried this, it is just a theory and the h2o2 is certainly the better choice unless you just want to try something odd.