Hello there!
I can generate new keys. I have 2 methods for that.
first method;
1 -power off the server,
2 -create an ami out of it,
3 -launch a new instance with this ami, with new keys.
second method:
1 - launch a new (temp) instance with new set of keys,
2 - power off the server, detach the root disk volume,
3 - mount the volume to the newly created temp instance,
4 - update the auth key files in mounted volume with the files existing in temp servers.
5 - detach the volume from temp instance, attach it back to actual server.
6 - power on the machine. we should be able to access it with new keys now.
7 - power of the temp instance as it's not serving any purpose.
and, I should be able to help you in 1,2 hours. please get back to me if interested. thank you.