Slept together.. friendship fixable?

My guy friend at work and I have slept together a few times (yes I know you should NEVER get together with a co-worker, bad news i know!).. and when we are hanging out together out of work we talk like friends, but at work he never flirts anymore and rarely talks to me. I am the only one to call or text etc.. Is there any way to get things back to the way they were, back when he actually seemed interested? How can i get him to actually come after me again, instead just me after him now.. Maybe even him to ask ME out.. novel concept i know i should have tried that BEFORE sleeping with him ... Grrrr haha this no bueno! (** by the way, i've always had a no-coworker policy, and a no sleeping with someone just because it sounds like a good idea policy until him**) (and neither of us are in highschool/college if that helps with your answers at all)