Extend PDF Due Date

I have shared a PDF for comment with external (not in our server) users. When I shared originally, I added a due date. Many users have requested an extended due date. Adobe is not giving me the option to change the due date. I was going to unshare in order to change the date and then reshare, but it warned me that the comments would be deleted.

My workaround would be to download all comments that I've received so far, unshare, change/remove the due date, and then reshare. This creates a new URL, however, and may confuse some of our commenters.

Any ways to update the due date before I continue with the workaround? Any help would be appreciated!