The saving function in the game is automatic, therefore you don't need to bother with clicking the Save Button.

However, the following can cause your game to stop saving your progress, which will result in a rollback (the game will rollback to the last saving point the next time you refresh the page or open the game):

1. Too many cookies and cache in your temporary internet files folder. Please clear your cookies and cache, learn how to do it HERE.
2. Many other web pages and programs opened on your computer. Please close everything that is not necessary.
3. Slow internet connection. Please reset your router.

You can verify if the game is saving by checking the Save Icon on the top right of your game window.
If the grey disk on the top right turns blue, it means that you can click on it to save the game. The game will automatically save anyways, and it'll become grey again after saving;
If it doesn't change color, it means that if you refresh or close the game, your progress will not have been saved and when you restart the game, it will start from the last saving point.