The pfBlocker package code should reinstall cleanly automatically after an upgrade, and normally does.
But note that pfBlocker "disables" itself after being installed/reinstalled/updated. It is "special" in this way (other packages just install and go if there are settings in the config file already). For pfBlocker, you have to go to its settings page and enable/save.
But there is no harm in uninstalling first, then upgrade, then install again and enable. It just should not be needed.