How to publish the changed timetable?

You can use the publish process again, just specify different valid from and valid to dates during the publish wizard. If the previous timetable is no longer valid, you can change the valid to date from the old timetable. But this is not necessary – if there are two timetables valid for certain date, the system automatically uses the newer one. So if you have a timetable valid for the whole year and you just want to put a special one for week, you just need to publish the new one for that one week. The user will see the actual timetable and bellow it link for older timetables