Did you do them all already? I would just trim the frosting sheets back to fit the icing if this does not impact the design, as they don't stick all too well to naked cookie dough. It would be easiest to trim as you go (as opposed to already stuck on the cookie) so I'm hoping you didn't stick them all already. You could also potentially pipe a border to conceal the overhang, but test first on one or two, as sometimes wet icing can lift the edges of edible paper (more so with wafer paper than frosting sheets though).
Also, do you have a picture you can upload (attach to a comment here), as it might stimulate some other ideas?
Best of luck!