Can you supply more information?
Was is it just the app that reset? (By reset, do you mean restart?)
Was is it your phone that reset? (I am assuming you mean restart. When I see reset, I'm going to think it was rolled back to factory.)
There is the option to turn mobile data off. This will only leave calls, voicemails, and texts coming through your carrier's network.
(Settings > Data Usage (Slide to off.))
Alternatively you can go to the Play Store > Settings > Look in the "General" section for "Auto-update apps" can be set...