See my screenshot above how you check which layout is active!
System->Compare two values -> LayoutName equals <your layout name>
Instead of having separate variable for each level (Level1, Level2, Leve3 etc), just make one global variable LevelProgress.
Add 1 after completion of each level to it.
In your LevelMap check the value of LevelProgress and unlock next level icon. For example if LevelProgress=2, then level 3 is unlocked.