shipping methods don't revert to cheapest

If someone orders a subscription and chooses a drop-off point as delivery, everything goes fine. The problem occurs on the 2nd shipment of the subscription. A new order is created in Shopify, but the delivery is changed. The shipping point is no longer selected as in the primary order, but the customer's address is used. I need the repeat orders to select the identical delivery method, i.e. the specific dispatch point selected by the customer in the primary 1st order.