As an automated upgrade? No.
I think it may be possible manually, but it would involve replacing every package and the kernel. It is hard and very prone to errors. I'm also not sure the result will work very well. I wouldn't do that on a server!
Anyways, if your disk crashes or if someone deletes everything on it, what will you do?
Take note of what applications you have installed, backup
/etc to save your configurations. Other parts of the filesystem may also be useful depending on the software you're currently running on that machine.
For the databases, dump everything (and don't forget the authentication and authorization tables). Database dumps are quick and easy to restore.
Reinstalling the same applications is not long and configuration should not be a problem if you have the old
/etc in hands.
If this is a web server, don't forget about places like