Override Pricing on Previous CSV Imports

Hello Everyone,

I have been conducting CSV Imports for different chain accounts that we do business with who have controlled pricing from a corporate level.  I conducted imports with the internal ID for the customer and items, along with the price level and unit price.  This has been a huge time saver when imputing sales orders for these accounts.  We have negotiated new pricing on many of our items and I cannot figure out a way to override old pricing and import new pricing.  As of right now we have someone manually updating each customer record when a price change goes into