I'm 19 and when I took my GCSEs my mum promised me a Mac Book Pro if I passed them all.
It gave me something to work towards, and kept me motivated knowing that once the exams were over I had something that I really wanted coming my way.
I'd maybe tell her you will get her one if she continues to revise well and works hard, but don't mention that you've already got her one. Maybe take her to a try on appointment to make sure it fits.
Then give it her after she's finished her last exam, from my experience she will be over the moon!
It gave me something to work towards, and kept me motivated knowing that once the exams were over I had something that I really wanted coming my way.
I'd maybe tell her you will get her one if she continues to revise well and works hard, but don't mention that you've already got her one. Maybe take her to a try on appointment to make sure it fits.
Then give it her after she's finished her last exam, from my experience she will be over the moon!