No you wont have to burn a new image, you can just upgrade on Kubuntu.
Its easy to do with no command line involved.
But the command itself is still very simple and you can copy and paste this command:
sudo apt-get update && sudo apt-get dist-upgrade
and then:
sudo update-manager -d
its that simple
As for disk burner yes i was referring to the tool you used to burn disks, the tool you used imgeburn is okay but sometimes tools like that dont work too well on burning .iso files.
The best free one and the one that ubuntu recommends is
http://infrarecorder.org/, a very handy burning tool for any distro (its not ubuntu speciffic).
Just watch those burning speeds, the slower you can burn the better.
I know these days many say the faster the better but not with .iso image burning, it often makes coasters with that method.
Its why I use USB drives, if you need more in the fuuture you can buy morer, these days they can be found real cheap and are a better investment then burning dvd's or CD's