If a record meets the criteria for a reminder to be sent out then this can only happen once even if the record is changed to meet the criteria again at some point in the future. For example, you may have a reminder setup to be sent out one month before a requirement is due, if you then allow the applicant a time extension but they've already received the first reminder, they will not receive a second reminder when the new due date meets the criteria again.

It appears the only way to ensure a second reminder is sent out is to recreate the record which is hugely time consuming if this has to be done in bulk (and is a requirement which has been published to web and potentially already started by the applicant!).

Can BBGM be rewritten to allow multiple reminders to be sent out?

Also this 'functionality' doesn't appear to be documented anywhere.