Maybe try this:

Playing fetch outside, time to come in, dog doesnt want to... You go to open doorway and present a food treat, like a hot dog or something good. Call his name or your recall, "here", its a trade off, good times for food. Dogs will usually take the food. He will prolly spit the ball out and come at you like a crazy man, back yourself inside the house while is coming, then give him the hot dog and close the door. Pretty soon he will be watching you to see when you go inside, and wonder if you have a hot dog or something good...