It's hard to root cause the problem without having the xlsx sheet you are using in your program. But in general this error is thrown when you are trying to access an array index which doesn't exist. At line number 229, you are checking condition, for allepunkte = 1:8, and for that it throws error that index exceeds array size of 6. So program will throw error for any value greater than 6. Try allepunkte = 1:6 at this point and check if you still see error. It's not the solution, it's just a way to root cause the error.
If this doesn't throw error and you have to keep allepunkte = 1:8, then you need to investivate why you are not getting cell arrays of required size.
Hope this helps.