My daughter is also 15 and her injury occured 4 months ago. I've got to two stories to share that show small improvements.

The other night, she was very engrossed in a book - which in it's self was an improvement. Knowing that she would stay up all night reading, I asked her to give the book to me to remove the tempation. She was being difficult about it, so I gave her 5 minutes to put the book in my room otherwise I would take it away for a very long time. She complied and then went to bed. A few days later, she was complaining that she had nothing to read. I told her she could finish the book she gave me. She broke out with a smile on her face and told me she had already finished. She inisted that she didn't sneak in my room and steal the book but didn't remember when or how she finished it. I asked her questions about the ending and it seemed she had read it. I was really preplexed for days how she managed to finish without me knowing it. Eventually, I pulled out the book - opened it up to her book mark and realized I had pulled a fast on. She had swapped the dust jackets with another book and gave me a different book! Her cognitive skills have to be improving, if she could come up with a creative way to trick me. Most parents would have been upset by this - I was thrilled!

Tonight, she took the time to actually do her normal teeth brushing routine (brush, floss, swish, clean the retainers) for the first time since her injury. She just hasn't cared very much about the personal care things (shower, teeth, hair, etc). Some day, it was tough just to get her to shower, comb her hair and brush her teeth.