From you question i can only understand that you are polling from server. Repeated hit will drain your battery very fast and will exploit user bandwidth also. With this kind of mechanism there are changes that your app will be uninstalled very soon.
So, what i will suggest use push notification ,if there is any update let server tell you. There is no need for client to ask for it.
One more way but complicated both at server and client side is you can open your own TCP socket
and can then you can share as much data in both direction.
I can suggest you to go with push-notification
for easy implementation and do right thing.