Yoinked from dotnot.org: all you need to do is dump the repository, like so:

svnadmin dump /path/to/repo > reponame.dump
tar zcf reponame.tgz reponame.dump


Copy it to the other server, in whatever way suits, eg:

scp reponame.tgz hostname:/path/to/new/repo


Then set up the new repo on the target server:

cd /path/to/new
svnadmin create reponame
tar zxf reponame.tgz
svnadmin load reponame < reponame.dump


That’s it! Piece of cake