Perfect 5/7 :)
I first thought about adding lives etc., but then realized I wouldn't replay the world if I used them all up and had to replay the first levels. However, It WOULD be possible if you would add a world map with level selection, lives and points: Upon game over, the levels already unlocked would still be accessible/selectable on a "continue" on the world map, but the total score would be wiped (100 points per food, -1000 points per life lost, 50 starting lives). Additionally, keeping record of the time for each level could be displayed on the world map (Let us beat your own best times xD).