Extended usage time for a pass

Hello! I'm looking into buying the 4 days within a month pass, however I need to be able to use the 4 travel days in a 5 week period (from March 24th to May 2nd). I don’t want to buy the 2 month pass because I don’t really need more than 4 or 5 travel days within those 5 weeks. Is there a way to pay a bit extra and extend the usage time? (so I can use the 4 travel days within 1.5 months for instance).

Thanks!