No need to reinstall... do you use standard paths? (/var/www/html/fop2) ? IN the FOP2 Manager, check the Plugins section, open config for "FOP2 Manager Autoconfiguration" and be sure it is set correctly.
That is the script that is run if you reload FOP2 from the Action menu. The Asterisk reload is detected but only on some Asterisk versions, as many new versions are buggy and do not advertise a reload via AMI at all. In those cases, you must trigger the reload via the Action menu.