Hi!
Yes, you can create the rewrite version. Just label it as such, either a bracketed mention in the summary, or in the title itself. As long as we know it's a rewrite, we don't treat it as a duplicate story.
Update the new version, and when you've finished rewriting the chapters, let us know so we can merge the hit count data and reviews from the old version to the new version. They won't overwrite any of the new reviews, so you keep old and new, and the count data should be combined, as I understand it. That's been my experience, anyway.
Thanks!