SO using Adv pricing not to reprice for an item on exiting SO

Is there a way in Advance pricing - where you have items set not to reprice on an existing SO, eg. if a customer on Aug9th was charged $100 for an item based on the item ctg code = A1 (based on setup price by item ctg cd on adv pricing). Later in Aug15th item ctg cd revised to A2 where the price now is $110. Is there a way to have this existing SO not to default the new price 110 but pick old price 100. only on existing orders and not on new orders. As new order