Take your forks off, take the top cap off, turn the forks upside down over a catch pan, pump the piston a few times to clean it out, refill to spec, pump the piston a few times to refill it, recheck oil height (add when needed) put the cap on 3/4 tight, put the forks back in the triples, tighten triples, tighten fork cap.
Done and done.
Btw, how old are your forks? If your seals are fine, I wouldnt worry about them.