Could the Price List to be Updated from the sales Order (Sales Line Price)

Hi to every one

I have an issue relevant to the sales Price list that needs to be updated for a specific customer and related items such that it is being kept updated all the time

and the price getting updated from the latest Sales Order (Sales Line Prices)

in other words, the user needn't keep updating and changing the sales price in trade agreement journal or else the system should remember (and Default) the latest price  

about this customer with the related item price correspondingly 

your help and support is highly appreciated