Is she into crafts? The small consumable bits are very useful to get a few different things - ribbons, nice pencils/markers, rhinestones, nice buttons, different coloured Hama beads etc.
I got DD a tub of silly putty stuff in neon yellow that I think she'll enjoy.
Some small jewellery bits? Or makeup items?
Is she into sports? Need an extra hockey ball (maybe a coloured one) or some mad funky socks or something like that?
We always (even still) get at least 1 book - always a fiction book, sometimes a factual book as well, maybe an annual or Christmas special edition of a favourite magazine etc.
Does she collect any cards/stickers/moshis/Lego people etc? A pack of whatever she is into.
We also always have sweets and fruit in the stocking as well, and I know lots of others who put the portion packs of cereal in there - obviously something that Mum would NEVER allow DCs to eat!
I would also never allow DD to get those awful aliens in a plastic container surrounded by slime - Santa brought 1 to DD 2 years ago, and a baby one arrived last year! Dreadful yokes (I really am not a fan anyway, but play up everytime she asks in the toyshop!).
I will toddle off and see if I can cull some ideas from my monster list (compiled from a US forum a few years ago - where they do stockings even for adults!) and come back in a while....