For the most part all a girl has to do to get a guy off is be there. But if you want to know if he wants more just ask him. Let him know that you apreciate all he does for you and you want to be sure to do as much for him.
The most erotic part of a persons body is their brain (I won't get into the metaphysical complications that statement brings up) talk to your man, an open and honest exchange of ideas will be good for both of you.