Some of my other games have a feature that allows the game to resume play after you have to leave it. That would be such a great feature for this game especially since some of the levels require sooo much time. To have to restart a level new each and every time is a turn off.
If you play on computer, it is not possible to resume a level since it's not saved on the browser.
On mobile though the level and what move you were playing is saved for some time, so you can go out from the game and then come back and continue with the next move. How long the game play is saved until it reloads depends on the device you play on and how much cache memory you have at that moment.