The next Ubuntu version 11.04 Natty Narwhal is coming soon, if you intend to upgrade to 11.04 from current Ubuntu version there are 4 ways you can choose including online and offline upgrading.
Note: Make a backup of the sources, softwares, and important data, upgrade may cause something incompatible.
1.) GUI upgrading with update-manager
This is the most normal way to upgrade Ubu
I tried looking for a way to upgrade the KDE plasma version of my Kubuntu 15.04 Beta 2 to the latest one, 5.3. But there isn't much reference online about how to do it, expect using Unstable Kubuntu PPA which is quite highly unstable.