How do I write a top-level conclusion?

What seperates an average conclusion from a top-level conclusion is whether the student can draw original insights from their own arguments. Most A-level students will simply summarise their argument in the conclusion, or perhaps, restate that same argument. A top tier answer will address the problem raised in the question and demonstrate how that problem has been resolved through the student's analysis. 

The key thing to remember is that a top-level conclusion will not bring in a new argument or restate the existing one. Instead, it will draw fresh analysis from the existing argument.