From what I've seen you're changing how the story is told, not just the art, so I'd create another series on tapas to keep the old pages there and delete them from the actual series (and upload the new pages there, so you keep the followers and all that) or I'd create another series and upload the revamped series there directly, letting the old series rest with a link to the new series at the end of each chapter or something.
Good luck <333 The art looks stunning, I'll keep an eye out for what you do 