Based on what you say I am at a loss at what or where your ship/route is then. The following screenshots show what I find in the mission editor in the Aarhus, Denmark vicinity. Either your Aarhus is not my Aarhus, or you have different campaign files.
I am not exactly sure if it is removed 'no matter what' from the world at that particular time/date. Maybe it started it's voyage before september 1st and is allowed to finnish it. So the end date could just be the end-limit of it's spawn-window. Haven't fully investigated that part. But I'm pretty sure it won't spawn after that time/date.