Okay, so I realize that he had to regenerate during the sixth season, but I recently saw the seventh season episode "Imperfection". Inwhich Seven's Cordical Implant malfuntions, and because it's broken she can't regenerate. Well to save her, Icheb gives her his implant. You can go on Memory Alpha to learn more about the episode or just watch it.
Now he's surviving without an implant, so does he need to regenerate anymore? Because it seems that it's essential for regeneration.