Stop the broker monitor on that machine, typically with a call something like

path-to-broker-install/S45Broker65 stop

Then edit these two files

-broker-data-directory/awbroker.cfg
$ACTIVE_CONFIG/awbrokermon.cfg

and replace references to the old port with ones to the new one.

Bring the broker monitor up again with the call

path-to-broker-install/S45Broker65 start

and verify things are up by checking

ps -efx | grep aw

You should see an entry for the broker monitor and one for each broker server you have.