http://www.subsim.com/radioroom/showthread.php?t=111150
Look here. Some discussion on the "Ground Hog Day" effect with the repeating mission. We are attempting to get a handle on it. Recap:
Seems there are only two missions per port.
When your port falls then you get another home port and new missions.
PH never falls so what then? We do not know as yet.
What I did was refit at another port (could not end patrol) and headed out on my own. I finally got a message with new orders. I'm still in the process of figuring out the ground hog day effect.