Have you tried giving her a shower to help loosen up any leftover skin, that may help. Also as I understand it as a cham gets older they stop having full body sheds and begin to shed in stages so it can seem like they are in a constant shed.
I would also give her back the (clean) laying bin, that way she will have it when needed, and you will not have to worry about looking for signs of her being ready. Just a thought