It sounds as though she is a bit lacking in passion - I find hooking up with amazing stylists producing amazing work massively inspirational and it makes me want to learn. Also seeing how much can be earnt is hugely inspirational, one of my peers has just outright bought herself an audi, from just working her butt off. You could find out what she'd like to do more of - colouring, bridal hair, precision cutting - and reach out to some other influential stylists in your area and see if she could get some work experience assisting them, this might give her a bit ofzest for the job again?
Maybe get her to follow some inspirational stylists on social media (I'm assuming shes young and uses her phone?) and sign up to BehindTheChair's email newsletter - maybe go through some of their step-by-steps with her and encourage her to look at how she would do these colours and then how they actually do them.
Maybe get her interested in her own self promotion - I was in a salon for a long time where i felt very much like the older stylists were better than me and I wasn't good enough. Book her in a morning colour and and afternoon colour maybe, and see how she works with a bit more time. Maybe ask her how she'd feel about, only while she speeds up, asking her clients to come back at the end of the day or the morning of her day off to have their hair photographed? Because photos on social media bring in clients.
It sounds to me like she's lacking in inspiration, creativity and passion - but all of these things can be ignited. Ask her what her dream hair to create would be, get her to find images, research how to do it, what base to put it on, and then work on getting her to be able to create this on a client or friend or junior. The satisfaction will buoy up her confidence and once she's finished her project, she can find something else she wants to work on. Make her see why she chose to do hairdressing, whether it was to create beautiful hair or make people feel amazing about themselves - if it's not either of these, follow what was said about and take disciplinary action, as she's also not making money.