But exhort one another day by day, so long as it is called today; lest
any one of you be hardened by the deceitfulness of sin: Heb 3:13
Sometimes the thing that really encourages someone is just taking her out for a cup of coffee or by giving her a quick call. Showing her that you want to know her better, to spend time with her, can give her the feeling that she is worthwhile to know. And since God made her and Jesus died for her, she does have value.
What is truly even more of an encouragement is inviting her into your home for a Bible study. The fact that you cared enough to welcome her into your home says a lot to her about the value you place on her soul. And you in turn are encouraged as you watch her learn and grow closer to our Savior.