I am asking around for a work around to help you but I see this as a feature request that is planned in the Idea - https://community.tableau.com/ideas/1713 and I suggest you vote for it too.
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Newer versions of Tableau do include the option for automatically setting Date filters to the latest date when the workbook is opened.
This would then pick up new (later) dates added to the data source and use the latest as the default filter value. You'll need to convert your field to a date value for this to work.
One possible calculation might look like this:
DATEADD('week',INT(MID(STR([Sem Code]), 5,2))-1,DATE("01/01/"+(MID(STR([Sem Code]), 1,4))))
Hopefully that helps!