AWS Micro instance: upgrade to Medium?

I'm running an AWS Micro instance and I would like to upgrade it to a Medium instance.

One way I could do this is just to bite the bullet and admit that I'll lose some of the traffic: stop Micro, create image, create Medium from that image. Should take 5 minutes, that's acceptable (for me, given circumstances).

However the problem here is the domain name. The Medium instance will likely have a different IP and then I have to point the domain name to the new IP, and that might take hours. That's not acceptable.

Suggestions?