You can easily upgrade your distribution using fedup:

First of all install the fedup package:

yum install fedup -y

Before starting the distribution upgrade you should be sure to have your system up-2-date:

yum update

If there are kernel updates etc. in the above update, you should reboot your machine before continuing.

Then start the upgrade:

fedup-cli --reboot --network 20

Whereas 20 corresponds to the currently most recent version – codename Heisenbug – you should change it accordlingly.

For a list of available distributions, have a look here!

The reboot option is optional, but will restart your machine once the update is completed!