Crashes on MC Home Screen

If click on the app, and it shows me the white loading screen. Then in takes me to Minecraft's home screen, but after only about one second it crashes. I have uninstalled the game many times, and it works after that but if I make a world and play in it for a while, then close the app and open it after around a half an hour, then crashing returns. I really do not want to have to delete my worlds constantly just to play Minecraft. How do I fix this?