I wrote the following below in reply to another question, but I think you should try it too.
I've never experienced the problem you are asking about and I think thats because you've got product/glue build up in your lace.

"Soak the whole piece in Autoglym Tar & Adhesive remover.
It won't harm the hair or piece and the glue will turn to jelly and be easy to remove.
http://www.towsure.com/product/Autoglym_...over_325ml "