You said she used the money to treat friends and buy stuff. How about let her experience some real jobs, so she can value the hardship of working for a living. Also she'll get a chance to earn her own money and able to do what she likes.
For her age, she can do small business like selling sandwiches/juices,or offer services such as clean up neighbours' yard and ironing clothes.
Let her experience the adult world and perhaps with that, she'll be matured enough to stop thr stealing actions.
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