I've sent items "back to draft" before. The automated statement that appears when I do this is that download access for past purchasers will be disabled while the item is down. It also recommends prepping all of your changes in advance before you send an item back to draft to minimize this down time. I do not know if past purchasers retain their online cloud access to your products on Roll20 but I assume so (which would be a reassurance to customers). In my experience, the review people tend to work quickly for product management. Just leave a note attached to the product when you forward it back for approval stating the changes you've made. It used to be you had to contact creator support for most edits but it has been made easier with updates to the interface, allowing for better independent control. There doesn't seem to be a set up for version updating yet (like an early access for module campaigns), that would be weird but nifty. Like more of an indie developer support system.