Well if your playing mid-game and the ipad crashes it's really a 50% 50% chance of saving, the best you could do is auto-save (or save every couple of minutes). But as long as you save all your data to cloud, none will be lost. Here's how you do it!
Connect the iOS device to computer, open itunes and choose the device.
Click Apps, scroll down below the list och bought apps and there should be a heading called
Sharing or Filesharing
"Apps in the list below can share documents between the iPhone and the computer"
Click Minecraft PE
to the right there are now a folder symbol called "games"
click to highlight this folder
scroll down and choose "save to..."
when restoring click "add"