Hi Tormodnoreng,
GRE seems to be the best option by consensus, but that's about it. Other than that, I think your only viable option is to lean on your application package. If you throw some fantastic essays at them and your creative material is on point, that could go a long way in convincing them that the grades aren't truly indicitive of your intelligence and/or commitment. I'd also "hang a lantern" on the GPA in your essays. Be open about it, and explain to them (in more subtle terms, I'd suggest) why they should overlook your GPA. These are creative people determining admission to a creative program. They're no strangers to very talented people with bad grades. You just have to convince them that you have the skills and commitment to compete with the other talented people with good grades.
I'd also suggest making your CV as well-rounded and unique as possible. Show them that if they reject you, they're not only rejecting your talent but also your perspective and experiences which contribute to creating a unique artistic voice. You also want to convince them that the version of you that had the bad GPA will not be the version of you that shows up at their school in August, January, or whenever. While GPA is not the #1 factor in an applicaiton, most schools have a pretty specific GPA minimum that you have to keep in each class and cumulatively. You want to assure them that, should they take the chance on you, that you won't be a student testing the limits of this requirement. You can do that by showing you're committed to a lot of other things in your life.
Obviously, you can't change anything that you've alread submitted, but this could apply for schools with later application deadlines or next year, should this year not turn out the way you want.
Hope this helps-- good luck on the GRE!
