The process of reassessing the value of a loan after it is issued. Before issuing loans, banks usually evaluate the borrower's credit status, repayment ability and collateral value to determine the risk and value of loans. However, after the loan is issued, these factors may change, for example, the borrower's credit status may deteriorate, or the value of collateral may decline. Therefore, banks need to re-evaluate the loans they have issued to determine their current risks and values.