can you re-clone failed clones?

ok, tried cloning 3 weeks ago, they all failed due to lack of humidity i think as they had no dome over, also over watering may have helped as the cut went black. we pulled them out of the cube and only 1 (from 17) had any signs of root growth. (even that 1 wasnt rooted, just a little tiny ending from where a root would of grown from).
the clones themselves are still growing new leaves and growing upwards. so was thinking just cut away the black ends and retry???? anyone done this and had success?

they can't be growing new leaves if they don't have roots. See the eye doctor for further assistance.

You could cut the brown end off and drop them in an aerocloner.. i have done that with failed clones.