Pocket Edition App keep shutting down

Playing pocket edition on an iPad2 an infinite world, I have updated with the most recent updates, since the version9.0 has arrived this problem has started, when playing, the app will with out warning shut down and I will have to open the app again, when I do the game will not start from where I was but approximately where I was 10 to 20 seconds prior to the shut down, however anything I built or picked up in that time is often lost, things taken from chest do not reappear in the chest, I can play the game for an hour before this happens or I can play it for 5 minutes and it will happen, I can not always tell when it will happen I only know that it will defiantly happen. Please help