Don't just seal it up, sort it out. I'm not sure what it will take to get it out, but once it's out you have some choices.
There are some expanding rubber plugs that will fit just about anything. Get a few, they get old and hard as they age, but if there are any threads left at all you should be able to use one easily.
http://faq.f650.com/FAQs/Photos/EnginePhotos/SumpPluggim.jpgThey also make oversized plugs. Over time, a little over-tightening here and there can add up to enlarged threads that are still pretty good but just too big for a standard drain plug. The oversized ones are a touch larger and will fit if your threads are still pretty good. You do need the right diameter and thread pitch, and I think the RE is an odd size, so it may or may not be an option.
http://www.oreillyauto.com/site/c/search/Oil+Drain+Plugs+%26+Gaskets+-+Universal/N2347/C0023.oapThere are self tapping oil drain plugs. Get the right size.
https://www.belmetric.com/dp14x15r-metric-drain-plug-p-5037.html?zenid=pg053qolmanvah4i7182kgo8a3&gclid=Cj0KEQiAwPCjBRDZp9LWno3p7rEBEiQAGj3KJnpJUCqOhc2BMkIvp_iu7pIczZjD02-jkSDhv0-n8YwaAtDU8P8HAQThere are also some that are a self tapping large center plug that goes in once and stays. The center of it is smaller and tapped for a smaller bolt that is now your new drain plug. These are a good solution but usually sit a bit high inside the drain pan, so you don't get everything out of the bottom any more. Still, better than leaking oil everywhere.
http://www.lawsonproducts.com/lawson/Self-Tapping-Oversized-Oil-Pan-Repair-Plug/93210.lpFinally there are the thread repair kits. Heli-Coil and TimeSert are the two big names. Heli-Coil is sort of a spring of threads. You tap a hole, screw in the spring, and then the bolt fits into the inner threads of the spring. TimeSert is similar but is a solid one piece insert. The Heli-Coil is cheaper, the TimeSert is a slightly better solution. I think the Heli-Coil oil pan kits are pricey, the spark plug kit is less expensive. As long as you have a washer and drain bolt that will fit, no reason not to use the less expensive one.
Both of these come as parts or a full kit. The full kit will have the tap, one or a few threaded inserts, and a tool to put the insert in. That's what you want. If you need more threaded inserts later, you can get just the parts and not the full kit.
There are also 'liquid thread repair" kits from companies like Permatex. I'd skip that option. Not the strongest or leak free option, not great for something you'll be removing and replacing repeatedly like a drain plug, and just try to get all the oil off the threads to get it clean enough to stick. This would be the worst option IMO.
Scott