Accounting for a revalued impaired asset

Currently the accounting for a revaluation of an impaired asset produces two entries to the value of the revaluation to the revaluation reserve.  

e.g an asset with the cost of £12,000 and an impairment of £250.00 revalued by £1,200.   Produces the two lines of £-950.00 and £-250.00 to the revaluation reserve.    We would like the line of £-250.00 applied to a different account (Impairment Expense).   Please could anyone advise how we could achieve this.

Thanks