Commit her to prayer first, in your prayer closet, maybe for 30 days- just pulled that number out of my head. Fast on her behalf. Get to where you really have a spiritual investment in her life in your heart. As you pray FOR her on a daily basis, you might see the relationship change. There will be a real battle going on in the spiritual realm that you can't see. As you see each other, listen for opportunities to share God's Word with her. Let God do the work. If she is drawn to Christ, you will know it. If she is drawn away from Him, beg her to return to the Lord. She might never want to speak to you again, which is her choice. But you keep her on your prayer list. Maybe years from now she'll come back to the Lord. There is always, always, always hope for salvation.