You want it to DRY UP. So, keep it dry. No fluids on it, avoid full-immersion baths for a few day, make sure diaper is folded back from the navel, don't wrap baby up in too many layers so s/he is sweating. And you can use a hair blow-dryer on a low/warm setting, 2 or more times a day for about 5min or more--aim it right at the navel, not too close to the skin. This can help dry up that last bit of weepiness very fast. As long as the skin around it is not red/inflamed, and baby's signs are otherwise good, no need to worry. But do everything you can to get it to dry up.