How do i get my dog to come in after going potty?

i feel like i am always hollering at rasin to come back inside after he goes potty. he is 9 years old and only recently started doing this. i cant find him for 20min or more sometimes. i used to be able to trust him to do his business and come back in, but not anymore. how can i get him to do that without putting him on his leash?