How to rekindle with a girl who use to flirt with me?

If they hire her back to the store I think you should try and make an effort with her if you are interested in her. Maybe she really did come back to see you. If they put her in your department, I think it is fate and you definatly should talk to her. It won't be awkward unless you make it awkward so keep it social and fun and dont get to serious with her.