If you're really, really desperate to get her to clean up her room, you might try the expedient to which I have sometimes been driven. Yes, it's cruel--nay, abusive!--and it's important not to let the Child Protective Services authorities hear you have resorted to this. Still, it works, if you have the strength to withstand her screams of agony until she breaks:
Take away her modem cable.
ROTFLOL!
Oh, the cruelty.
I can recall a couple of times being doused by my dad with cold water when I refused to get up in the morning. I have now described "The Method" in chilling detail to my six year old. Haven't had to use it; the mere word is enough ....