I think you're looking for the "Recurring Documents" module. The technical name is subscription.

Quoting from it's manifest:

Create recurring documents.
===========================

This module allows to create new documents and add subscriptions on that document.

e.g. To have an invoice generated automatically periodically:
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    * Define a document type based on Invoice object
    * Define a subscription whose source document is the document defined as
      above. Specify the interval information and partner to be invoice.