How can I upgrade my ultimate edition from 9.0 to 11.4 without re-installation?
I thought it not likely, but Upgrade Ubuntu desktop | Ubuntu
You can install it on a new partition/drive and switch back and forth, so it would not be that painful. I do not know if there are migration tools, but if so probably for smaller jumps. Still, keep in mind that you may be able to google up a downloadable tool that convert config files for xxx from version X to Y.