Increasing the number of reminder snooze options in MacOS
Those notifications are managed by the Notification Center App Extension inside of Reminders.app: /Applications/Reminders.app/Contents/PlugIns/com.apple.RemindersNC.appex
and displayed by Notification Center. Sadly none of the information used to create the window is editable by the user.

Interestingly, there were more options when this feature was introduced in Mavericks. http://www.mactricksandtips.com/2013/11/change-the-snooze-time-of-a-reminder.html