First of all, you should remove all your KDE repositories (either from YaST or the configuration files). Then you should enter the following commands in order to add the newest repositories:
su -c 'zypper ar -f KDE_49'
su -c 'zypper ar -f KDE_Extra'

After that, you just have to type in a terminal/console:
su -c 'zypper dup --from KDE_49 --from KDE_Extra '

And then, Zypper will start downloading and installing software. When the installation is finished, reload the graphical interface and then enjoy your fresh KDE environment.

Have fun!