REVISED RETURN POSSIBLE?

OUR CLIENT FILED SERVICE TAX RETURN LAST YEAR BUT DID NOT CLAIM EXCISE DUTY PAID ON ACQUIRING MACHINERY FOR PERFORMING SERVICES.THE AMOUNT EXCESS PAID IS 48 LAKHS.CAN WE FILE REVISED RETURN NOW AND SELF ADJUST THE EXCESS PAID AMOUNT AGAINST THE LIABILITY OF THIS YEAR.IF REVISED RETURN IS NOT POSSIBLE IN WHAT WAY CAN WE CLAIM THE EXCESS PAID AMOUNT?