That would be a great feature. You should definitely suggest it as a feature to xero. But no, at the moment you can only set up 5 reminders. However many days past due is up to you. you could do 7/14/21/28/35 etc which would give you 5 reminders, one each week for 5 weeks.
Can you not set it up to keep sending at a set interval until its paid? e.g. send every 7 days till paid?
That would be a great feature. You should definitely suggest it as a feature to xero. But no, at the moment you can only set up 5 reminders. However many days past due is up to you. you could do 7/14/21/28/35 etc which would give you 5 reminders, one each week for 5 weeks.