I am sorry for rather delayed reply.
Though intention of the legislature is quite clear that 80G exemption is
now available in perpetuity till withdrawn by the Dept., however our experience
for getting this exemption in perpetuity is as varied as the number of states
(and sometimes even within states).
To be on the safe side, it is suggested that please get apply for getting
S. 80G exemption renewed and get an order from the dept. which states that it is
renewed in perpetuity till withdrawn. This is the safest.
Cases where dept. is not accepting renewal application should take it in
writing from the concerned oficer that it is not required.