You may have blown up the star ratchet, and they definitely can be replaced, and easily at that.
Take the wheel off the bike and take the skewer out. Lay the wheel down with the cassette facing up. Using both hands and a rag, lift up smartly on the back side of the cassette (someone may need to hold the wheel down for you, but I find that if I curl my fingers up with the knuckles resting against the spokes, the whole thing just lifts off).
This will expose the entire guts of the ratchet mecahnism and you can take stock of the situation- there'll basically be the two star ratchets, a spring or two and a large washer. Be careful to observe the orientation of the parts because they can go back in incorrectly with the result that you could find yourself riding fixed gear which will be disastrous for the rest of the drive chain. Somewhere on the DT Swiss website are pictures showing how this is all done.
I'd say that if you've broken a ratchet or stripped the teeth between the rachets, you can get replacements and be good to go. On the other hand, if you've blown up the splines that engage the rachets in the body of the hub itself, a new hub is in order. If the same splines in the part that mounts the cassette are the only ones stripped, that part can be replaced, but I'd say a new hub assembly would be a good idea.
I carry a spare pair of star ratchets with me (greased and ready to install) because this procedure can easily be done in the field if necessary in probably 15 minutes or less.
Also, it's a good idea to clean and regrease the ratchets at the end of each season.