Replace it? Nah id just fix the hole! Its a simple threaded hole and there are lots of ways to go on this repair.
Just DONT use any of those liquid thread repairer products in a tube...! They hardly ever work! Especially on an oil drain plug. So i wouldnt waste my time on this crap. Fix it the right way.
Use a heli coil, or just tap it out for even bigger bolt. Or tap it for a valve of some kind (but you would want to wire it shut each time when you are not changing oil so it doesnt open itself).
Lotta ways to go, heres oe.
http://www.napaonline.com/MasterPage...it+-+Universal
If the bolt within a bolt thing (link) started to leak, you could have it brazed or even silver soldered to stop the leak.
And worse case, get an oil pan from a pick a part junkyard if they have those in your area. (Least expensive).