Changing amount of shared memory via Bootcamp?

I installed a Windows partition to my Macbook 2 years ago so that I could install certain programs that are only available on Windows. I made the mistake of dividing my CPU memory half and half for each partition when I only needed just a few GB for my Windows disk. I now only have 40GB free on my Mac partition while I have 106GB unused on my Windows partition. My question is, is it possible to transfer GB from my Windows disk to my Mac disk without reinstalling everything? Thanks in advanced for your time!