MCPE v0.9.5 Worlds won't open after several days of building on iPad

i love Minecraft PE. My children introduced me to it. I bought the version for my iPad.

What I expected to happen was...:
For the game to continue running after days and days of playing and building in my worlds.

*What actually happened was
Ever since I started playing about 6 weeks ago, I start a world and have fun discovering it's secrets and building. After it reaches a certain size in MB, it freezes. I shut the program down, and restart world. It won't load. I've eve n restarted my iPad, nothing helps. It sits there a few seconds, and then closes down the program. I've rebuilt at least a dozen worlds. Both in Creative and Survival. I do not play multiplayer. Each one has stopped and won't load. Any suggestions?