How about going in with a big bin or container once a week, taking everything up off the floor, and putting it in "jail" for a month?
When my daughter was little, if she abused a toy or was misbehaving with it somehow, the toy would "go to toy jail" (say, up on a high shelf or in the linen closet) until she got her act together -- some age-appropriate amount of time. I think a month is a good time for a teenager, especially if what goes to jail is something like homework or a school project, and she gets a low grade.
OK, maybe only a week for school things. But what I think would work really well here is clothes, electronics, and books. I can hear my daughter now asking for her favorite pair of jeans, or her iPod, or a book she was in the middle of reading, or the outfit she really really really wanted to wear to a friend's birthday party. Because, well, if she really really really wanted to wear it, it wouldn't have been discarded on the floor, would it? She has plenty of dresser drawers and hangers and hooks in the closet.
Sorry, the OP was about accessories. Clearly, I have a personal problem with clothes on the floor, LOL.