They are so desperate to be individual and adult at that age, but not ready to. I did as many things as I could to help them feel like the transformation they were desperate for was happening.
Plan a makeover of her bedroom. Make a Pinterest page and get her to pin things on it that she loves, then work together to design it. Paint it together and go to IKEA together. Build the furniture together. Doesn;t have to be expensive, just a new duvet cover, some new posters for the wall etc or a full makeover if you're up for it.
Do the same for her own look. She might be at an age where she wants to look more grown up, Help her choose new styles of clothes and hair if she wants to and go on a shopping trip.
Go to see a musical or dance show with her. Or go to a gig of music that she loves.
Teach her to cook some basic dishes: pasta, a cake, chicken tray bake etc.
If she and you are into it, have a few home spa days doing nails and pedicures etc.
Do some projects that might help with next year at school: read some books and watch some films or documentaries that are related to the syllabus but fun. Do some fun science projects or nature research. Focus on her favourite subjects.
Have a reading challenge. Each pick a book. Both read it and discuss it. Same with a film. Same with a CD or streaming of a new album.
Do a few of the old childhood favourites - a trip to the beach or a funfair.
Climb a hill and take a picnic. At that age my DC felt very impressed with themselves if they managed a 10 mile hike or climbed a small mountain.
Take her swimming anyway. My DS was very embarrassed the first couple of times, then got the bug and we ended up pushing each other to swim a mile one summer when he was a tween/early teen. I have happy memories of that and so does he.