How Can I Get My Dog to Willingly Go In His Kennel Again?

My dog used to go in his kennel just fine every time I needed him to. I would say "kennel" and in he would go because he would get a treat. He became more difficult after a time and I had to have him follow the treat in the kennel and then shut the door. I continue with the positive reinforcement, but now every time he knows it's kennel time he runs to a corner of the house. When I go and try to coax him out he bites at me and becomes violent. How do I get him back to the well-behaved-kennel-loving dog he once was?