Fluffyduck,
I know it can be done, I did it years ago, but frankly found it easier to just end listing and re-do it. If you have a store and list for 5 cents that is what I would do.
I have to run out but when I get back I will see if I can remember how to do it.
In meantime, I would write support and ask them, as they may have a quicker way than I would and they may be able to answer you quicker than I can since I won't be back for awhile.
Vickie