Any suggestions as to how to treat a lovely 13yr old girl?

[Guitargirl]

My little cousin will be 13 in January and I would love to get her a special Christmas present this year. We live 3 hours from my parents but go there quite often and every time we go she comes round to spend the day playing with DD(3.10) and DS(1.10). DD can be pretty moody with her some days but she never complains or doesn't want to come. It really helps us out having her around and I would love to treat her to something special. Have tried to get out of her what shops she likes and she says Primark and BHS!! So, am at a bit of a loss - any ideas? I was thinking about JLS tickets but as I would need to get 3 (one for her, a friend and an adult) they are already out of my price range. I could spend up to £100. I think she's got everything 'gadgety'.

take her out for the day clothes shopping ? make it a fun day of trying out new styles etc - and you can buy her an outfit or something? my nearly 13 year old nephew prefers something to do rather than a 'thing' if that makes sense

What about a spa day, all girly.

Take her to have a make over and photo shoot.

cinema and a meal

just a couple off the top of my head

iTunes / HMV gift voucher for some of it? Then treats / makeup / nice bag / books for the rest? When I was about that age I was always really torn - loved being able to choose my own present, but vouchers / cash not as exciting to unwrap - so you could go for the best of both worlds!

She sounds lovely, makes me miss my little cuz, I haven't seen her for ages!

Topshop voucher

Take her for afternoon tea

A new purse with some money in it

Funky new duvet set (consult her mum re colours!)

A pretty but fairly classic bracelet or necklace so that she can keep it forever eg: a tiny Tiffany key or bean

Thanks very much for the suggestions - all great ideas!
She will be coming to London for Feb half-term with my Mum to stay for a few days. I might take her to Westfield for the day and let her choose something, take her for lunch and stuff like that. Or maybe Oxford Street and let her go wild in mother ship TopShop/Primark!