LW 5 does not have the ability to 'force' the incomplete files back into the download window. The only technique I am aware of would be to downgrade back to LW 4, force them to resume, then close LW 4, reinstall LW 5 again ... so make sure you still have the LW 5 Pro installer handy. See
Downgrading to LimeWire 4 from 5 & resuming incomplete downloads. You will lose the previous download % however. But at least they will return back to the Download window after using this process.