Please do not use the "I" word.
Joking, but really - I doubt its an infection.
I have made quite a few doppels, and they RARELY clear within a few MONTHS - let alone at all. I do not use any finings, I bottle carb everything - no kegs here. What I would say, is if you want that to be clear, wait.
Mind you, since I do not keg at the moment, I could be wrong but you might want to try using a wine kit clearing combo, and rack off into a new keg. Seems like a lot of work, and risks oxidization. Other more experienced keggers may pitch in...