Change the status of the contract to Draft. Make price changes on the original quote used to generate the contract and check Contracted on the Opportunity again.

Create a Price Book with Price Book Entries to reflect the new prices. Populate the Contract Amendment Price Book ID field with the new Price Book ID to generate Amendment Lines with new prices.

Clone the Quote Lines which need to be updated. Modified the desired discounts on the cloned Quote Lines. Update the original Quote Lines to a Quantity of zero.

Change the values for Net Price on the subscription or Price field on the asset. Amend the contract and use Refresh Prices.