Physical Therapy

My husband, who is now in his 6th year of being DXed with PD, refuses at all costs to comply with physical therapy programs at home. At least twice a year, I take him for the full PT sessions, so at least he is getting some benefit. I am watching him quickly deteriorate, and I have tried everything to attempt to persuade him to comply with his exercises. He is virtually refusing at all costs to comply. I go with him to PT and regularly have the therapist remind him of the benefits and the repercussions of NOT doing the exercises. Does anyone out there have any advice for me? I am at my wits end - I watch him suffer, move less, walk smaller, lose his balance, his strength and in general, he spends his days sleeping in front of the TV. I am willing to do ANYTHING to help him. Any advice would be appreciated.