Income tax exemption on gratuity

Dear Tax experts

I joined a company in 1992 and was laid of in 2013, after 21 year of service at the age of 53 years.  I received a gratuity and the tax exemption was for 10 lacs as per the tax rule at that time.  Now, I have started working again.  

Given that we are talking about gratuity and I am not retired yet and gratuity is a type of retirement benefit. Is there a provision to claim tax exemption as per the current IT provision of 20 lacs for the gratuity received in 2013 ?  Note that gratuity is once in a life time kind of retirement benefit and I am not retired yet.  

Please advise - Thanks - Ignesius