If you are using the 3 piece cartridge system, just pull the white filler out of the cartridge, rinse it with water, pat it dry with a paper towel. Let it try a couple of hours, put it back in the cart and fill with juice.
In the meantime, use your extra cartridge. You do have spares, right?
If you are using the 2 piece cartomizer system, about all you can do is take the end cap off and blow it out and let it air dry overnight or even 2 days if you got a lot of water in there.