Any advice on hiw to get him turned on?

My boyfriend and I have been dating now for almost 2 years and for the majority of time the sex was amzing. We could barely stop having it. For a few months now he kept losing interest. He said the sex on it's own is still amazing but the start up ist getting boring. It has come to a point where he won't start it on it's own. However he does not want me to start with a bj because then he won't last long enough. What am I supposed to do? What do you all do to get your man hot?