Preachers, speakers, and writers all like to re-use proven material. That can be dangerous, though.
My preacher father loved to tell the story of the time he used one of his old sermons without reviewing it first. Half way through, he found himself saying, “As the president said last week …” The problem was that “last week” was over a decade and two administrations before.
That’s a worst-case scenario. But even if you use old material that doesn’t have dated references, you should still review it and update it.
The audience is different and you’re different. You should update you material to reflect your current thinking and serve today’s audience.
Some writers edit the older material. That can be a good choice if you’re pressed for time. I prefer to write the piece over.
I read the old material. If I’ve got several pieces on the same topic, I read them all. That reminds me of good things I’ve said and, very often, I’ll spot new connections I never noticed before. Then I write straight through and edit.