At 15 years old, you might ask your daughter to see what she is drawn to from the paraliminals list in our "All Products" link on the website. There are taglines for each paraliminal that give you a good sense of the purpose and the possibilities for change inherent in each one.
That being said, though, based on what you've said above, I would suggest considering "Self-Esteem Supercharger, Self-Love" (which is being released this week), and/or "Belief" (because if you think you can or you think you can't you're going to be right).
From a relationship context, consider "Positive Relationships, Instantaneous Personal Magnetism," and/or "Automatic Pilot."
For general mental focus and acuity, "Peak Performance, Fresh Start," and/or "Focus and Concentration."
From a totally different context, have you taken a look at the "PhotoReading" course? Many children take to that like a fish takes to water and it really helps them recognize their innate capacities and intelligence - plus learning becomes fun again. Both my sons took that course with great effect. The one who is local took the class and my other one did the personal learning course.
Just a few thoughts. Hope this helps!!!