Oil leaks?

Looks like my mechanic just found a small crack in the bottom of my
oil pan

I had noticed a small amount of oil on the belly, around the front
gear well, and a small bit coming out the top of the cowling at the
oil access door that normally wasn't there.

Had him pull the cowling off and after a dye check, he found a small
crack.

Anyone have any experience with something like this?

Is there any kind of seal that can apply?
Welding options?
Cost of replacement?
Do nothing?

Any thoughts would be appreciated.

Thanks.

Daren