With respect to a regulated consumer credit transaction, the creditor may, by agreement with the debtor, refinance the unpaid balance and may contract for and receive a finance charge based on the amount financed resulting from the refinancing. The amount financed resulting from the refinancing comprises, if the transaction was not precomputed, the total of the unpaid balance and accrued charges on the date of refinancing, or, if the transaction was precomputed, the amount which the borrower or buyer would have been required to pay upon prepayment pursuant to the provisions on rebate upon prepayment, section 28-42-307, Idaho Code, on the date of refinancing, except that for the purpose of computing this amount, no minimum charge shall be allowed.