Instead of an Int for each level, I’d make a map of Names to Ints in your SaveGame class. That way you can add new entries to the map based on the level name without having a specific Int variable for each. And if you call the Add function to the Map with a Name that already exists, it will overwrite, so you can always save new data just like with the separate Ints.
Here’s how you create a Map (Simply create a variable, then click the dropdown menu to the right of the Variable’s Type, and select Map)