You should definitely not stop the lessons. Grade 5 at 12 is very good and she is probably very near a sort of break through in standard which could change her life. I don't mean necessarily be a pro - I mean once she is a really accomplished musician, she will be for ever, and it will stand her in great stead.
I can play the piano and other instruments and every time I do, a million people in the room say "I had piano lessons till I was 12 / 13 and then stopped and I so wish I had carried on". Don't let your dd be that person.
Instrument practice takes up time but it is actually very good for you, in a meditative way. It undoes a lot of the damage that daily stresses do to your wellbeing and equilibrium. Even boring things like scales and arpeggios are soothing. I think life is very stressful for teenagers and this is a way of managing stress, as some people use sport or running.
How to get her to practice?
- is she tired in general? Does she struggle to fit everything in? This is something to look at - can you re-jig the schedule so that she feels a bit more relaxed?
- if she is not a morning person forget the morning thing
- do a deal where something nice comes with or after practising. Not like a bribe but as part of the routine, that tea and cake comes after practice, or something like that
- is there anything uncomfortable about the room? Is it warm enough, do little siblings wander in and out being annoying, can you make it feel like a calm and sophisticated and welcoming space?
- can she do it instead of something else that she doesn't like? If she is in general overloaded, can something else be taken out?
I can remember as a dumpy (I wasn't really, but I thought) teenager watching someone who was amazing at gymnastics do backflips for fun at a picnic. I was dying of envy at being able to just perform and play like that, for the pleasure and the fun of it.
It dawned on me a few years ago that to some my apparently effortless musical skills are just as enviable and exotic. They are not effortless but just as that girl spent her childhood practising gymnastics, I spent it practising music, and it's in the bank now, forever. I wouldn't swap it for anything. Everyone says that. I just don't know how you can make it mean something to her