As great as it would be, honestly I don't think you can. You've been the one reaching out to him each time and you've acknowledged that he isn't showing much interest. Doesn't sound like there is much of anything to base your interest off of either other than your feelings from years ago; that is what is on your mind and is motivating you to keep trying. It's hard to let go of this... Focusing on the present with your polite talks shows it may be best to look elsewhere.