Reply speeches are the only four-minute long speech in World Schools. These speeches are meant to summarize the events that had happened in the round and explain why your team won the debate. The goal in the reply is not to make any new arguments. All of the argument construction should have happened earlier in the debate. That said, the prop reply should seek to answer any new content from the opp block.
The reply speech should “write the ballot” for the judge. A good template to follow for completing the reply speech is to cover the principle debate followed by the practical debate. You can also sub-segment the two types of debate out via topic (i.e. you can cover who won the econ debate, who won the foreign policy debate, et cetera.) Overall, the reply speech should take a big-picture approach to summarizing the round, while avoiding getting into the nitty-gritty questions of the round.