Is there anything I can do about the mental health limitation?

I am currently on LTD through MetLife for schizoaffective disorder. They have told me that due to a mental health limitation in my policy, my benefits are capped at 24 months. What can I do about this? Is there anyway I can request an extension? Realistically, is there anything I can do so that I can continue receiving benefits? I was thinking about a lawsuit, but not sure if I want to open that can of worms. Thank you for your input everyone!