A lot depends on whether you buy things for her very often, or only for special occasions such as her birthday. If you buy for her fairly often, then she doesn't have much reason to spend her own money--she'll just wait for you to spend yours. If you don't buy her very much, she'll spend more on herself eventually. If there's something she REALLY wants, and she knows you won't pay for it, then she'll get it for herself.

When I was young, I knew that if I didn't save my allowance for it, I'd have to wait for my birthday or Christmas, or I just did without it.
With 4 kids in the family, my parents rarely bought us anything (outside of birthdays or Christmas), that wasn't food or clothing. I wasn't always happy about that as a child, but I'm grateful for it now--it was a good life lesson.