What are the steps to upgrade?

1: save existing site configuration file, this will have to merged later:
/etc/blockhosts.cfg

2: run the installer, it will overwrite all old files.
Extract source, and run
  python setup.py install --force
OR use rpm command (change n.n.n to version used):
  rpm -Uv BlockHosts-n.n.n-1.noarch.rpm

3: edit /etc/blockhosts.cfg and if needed, update /etc/hosts.allow, to configure BlockHosts as required at the site