Rebasing individually based miniatures on washers and coins is easy to do without damaging the miniature, but the way i do it, you would have to re-texture the base: I just grip the base in a vice grip and then, on the opposite side, grab the base with pliers and bend so that the miniature pops off the base. Then i glue to the new base, glue down sand, paint the sand, and add flock. Off course, i have only done this with 15mm and larger miniatures, so with smaller scales, YMMV.
Those are brave men knocking at our door. Let's go kill them!