The easiest way for you to change between distributions without losing your data would be to plan before you install. By creating /home on it's own parittion, during any future distro changes opt to not wipe the entire disk and keep your /home directory in tact. That said, it sounds like you didn't do that.
You can keep your data a couple different ways. If you have another Linux system (even a Windows system booted using a livecd/liveusb) you can tar your /home and rsync it to the other system and later rsync it back. Rsync uses ssh protocol as does scp/sftp, so you'd only need to get a disk mounted and an ssh server started.
Another option would be to use a livecd and mount your currect Linux partition, assuming everything except swap is on one / (root) partition. Delete all the directories other than the home directory once and then during install, tell the new distro's installer to use the partition without doing a format. Your home directory and /home/ will still be in-tact. However your user's UID (number your username maps to) may be different after your new install unless you specify it to match when it creates your first user. You can find out your current user's UID by typing id in a terminal or using your system's gui tool for user management.