Not pretty but if there is new cover art and/or exact release date is known I think that’s okay.
Another way to handle this are recording series:
Biggest disadvantage in your case would be loss of existing cover art. 
That’s what I dislike about Bandcamp and the removal of RSS feeds
“publish_date”:“12 Oct 2013 20:07:14 GMT”
“mod_date”:“31 May 2019 04:46:23 GMT”
Just curious, are you eligible for any updates or do you have to purchase again?