No. SevenFifty sees every product file as a complete representation of your entire portfolio. All the products you wish to see on the site should be submitted - not just the changes.
To add a product, add a row to your product file and fill in all the product information.
To remove a product, delete the product from your file.
To make changes to pricing, make the changes to your file.
When you're ready, upload the file to SevenFifty.