If you're anti conserve, I'm going to ask you to do some heavy reconsideration and reflection, and see if that's really the right way to be. Think long and hard, okay?

The reading for 反 is all good. The reading for 省 is an on'yomi reading you haven't seen yet. Here's a mnemonic:

I'm standing in front of you, forcing a reconsideration of your anti conserve stance, with my saber (せい) to your throat. I better see some reflection on your face or you won't have one in a second.