We utilize chemical vapor deposition to demonstrate the reactivation of catalyst for multiple regrowths of vertically aligned carbon nanotube arrays (carpets) in the context of water-assisted supergrowth. The carpets are transferred from the growth substrate, and the catalyst and substrate are reactivated by annealing in air. Annealing parameters control the length and diameter distribution of nanotubes in the regrown carpets due to active catalyst termination followed by a size-dependent process of iron carbide particle reoxidation. The lack of achieving indefinite regrowth from a 0.5 nm thick Fe layer can be attributed to factors such as catalyst dynamics taking place during the growth and regrowth processes.