If she's interested in Hello Kitty, how about visiting Sanrio shop? There are several big Sanrio shops in Tokyo, such as Ginza and Shinjuku.
There should be Japan limited products.
Pokemon Center might be fun if she likes Pokemon. Ikebukuro and Oshiage (Tokyo Sky Tree) has big Pokemon Centers.
Harajuku Takeshita Street is the place where Japanese teenager girls go for clothes shopping. If your daughter is interested in fashion, there might be interesting, too. DAISO in Takeshita Street is huge and offers everything in 100 yen. Everything I mean, EVERYTHING. You can find anything you can think of at DAISO in 100 yen!