The correct answer to a strengthen question does need to provide new information. I cannot strengthen your argument by repeating what you have already said. So new information is required, but that does not mean that it needs to be a new topic or a new discussion, rather it needs to relate to the current topic and specifically the answer needs to link together the evidence that you already have with where you need to go (the conclusion).

You can think of the correct answer to a strengthen question as bridging the gap between where the evidence takes you and where the conclusion picks up. So you are not looking for something that is completely new. It should relate to the both the evidence and the conclusion, and should, in fact, link the two.

Here is an article that helps to explain that link: https://www.beatthegmat.com/mba/2011/02/ ... duncan-way