Thank you for your great advice you guys!
@Fewormany: good idea to start with one thing.
I think I am bored with both the lack of colour (but I removed colour from my wardrobe because I tend to get tired of coloured/patterned items more fast than basic items) and my wardrobe in generel. I think I need something to oomph it all up a little, since everything is just so basic and black and grey. I used to wear rockabilly dresses and Jeffrey Campbell Litas, and although that's definetly not me anymore, everything is just so safe - and therefore boring, ATM.
@Eizhowa: I was looking at a dress in a purple-ish print and actually put it on my wishlist for my birthday. It would be a help but I am not sure if it is an solution, since I tend to get tired of print dresses fast(er) than with other things.
Other than that I do not have a lot of things on my wishlist that screams "statement-piece", since I am currently looking for the perfect black skirt, black jeans, grey or navy maxi dress, a black sweater, black wool coat, and an ACNE Canada scarf.
Perhaps getting a haircut will help - I am getting bangs on Tuesday.