For each level, a maximum amount of 3 stars can be earned. All of the stars earned from the levels will add on to the total amount of stars needed to unlock a new island.
Important: For the stars in each level of an island, you will have the opportunity to replay the level to earn the maximum amount of 3 stars. For example, if you only earned 2 out of the 3 stars for a level, you can replay the level to get the maximum amount of 3 stars for that specific level again. It is important to remember, if you had 2 stars before and earned 2 stars again from replaying the level, you will not get a total amount of 4 stars. The stars do no add up from replaying a level if you get the same or lower amount of stars. You can only earn more stars by filling in the missing stars from that level.