If you want to change the amount of time shown on your public schedule page, just go into Manage Account => Reservations/Schedule Settings to change the time period.
It looks like this:
A bit of background:
Punchpass automatically creates your regularly scheduled classes 90 days into the future. The 120 days or 180 day options that you see above are so you can show workshops or classes that you've addded individually in the distant future.