Ability to create a sales order that is repeated on a weekly/fortnightly/monthly basis automatically
Reckon Accounts already has the ability to memorise (and auto-create) recurring sales orders (and almost any other transaction type for that matter).
Either right-click the sales order and select memorise sales order. To edit the memorised transactions, go to Lists > Memorised Transaction List
HINT
It is helpful to set up a GROUP for bundling memorised transactions that are created together eg end of month journals, or invoices sent on the same day every month.