(sorry for the long response time). So it would be possible to do that with some custom code. For instance, when your app creates a reminder, it can save a record in a database. When the reminder is dispatched, you could save a flag that says that the reminder has been dispatched. And on server restart, it’d be possible to lookup this database for reminders that were never sent, with a date in the past.
Is this a possibility for you? Does that make sense?