You have baby stuff, you have some kid stuff (which we can use more of that also) but you really don't have a lot of stuff for teenagers.
It would be great to have:
1- teenage focused posters and pictures (some male focused and some female focused).
2- school books
3- jewelry with holders
4- more hair accessories - this one for ALL ages
5- more wallpaper designs focused towards teenagers.
6- standing and wall decor items for teenagers
And anything else you can think of that a teenager would like.