I had the same issue with glue seeping from lace to the bottom half of hair. I can't find above 75% isopropyl alcohol so I have been soaking in 75% alcohol. It didn't do much in terms of removing residue from the hair, and so the hair was clumping together.
So I tried soaking the hair piece in walker solvent adhesive remover for around 30 minutes and then washing hair with shampoo and conditioner. I found the result to be significantly better. I was able to remove pretty much all of the glue and was able to style my hair much more easily. Yes, you need to use leave in conditioner daily to avoid hair getting dry. I don't soak all of the hair piece, just in 1/2 inch of remover which covers the base and the lower part of the hair.