Cenvat

if you have availed exemption under notification no 08/2003 anytime after 1995, that means lapse of duty on the time of exemption availment, 

if you have not availed exemption and paid duty on clearances in previous all years, then surely u can utilize the duty balance.

Refer the past period ER-1 returns and check the balance of credit in the returns, you will get the clear picture of duty still available or not.