Revegging a plant is easy as pie in most cases. Just flip the light cycle back to 18/6 and start a veg feed and wait. Once you get some fully revegged branches that have fan leaves with 5 or more blades you can start thinking about cutting clones. I typically don't like to flower a revegged plant, instead I would rather use it as a mother to cut a crop of clones from. I have had a strain that never wanted to fully reveg, maybe it had a little ruderalis in it's lineage but for the most part it's as simple as switching the lighting schedule. I wouldn't bother repotting it or messing with the roots unless it's root bound.