What should I do or say to subtly let him know?

There's this guy I have been deeply and madly in love with since I was 16, and I'm 18 now. What should I do or say to make him know or want me to? He's been engaged since I've known him, but with in the last month they broke up, so he's a free man. We rarely talk and I don't want to be obvious and always initiate conversation, but what steps should I take from there. He works at Panera, that's how we met because I used to work there, and so I think he is working Sunday, so I'm gonna go visit him there with my sister and just act like we're going for lunch. But I am having a hard time hiding all this. What do I do to either let him know I like him, or make something happen between us. He knew I USED to like him, but I don't know if he knows I still do.