| If you speak regularly, you will have a fund of stories that you use, examples that you quote, and people that you mention. It is a good idea to review these from time to time to make sure that they still resonate with your audience. You don't need to change that much (and may not need to change anything at all), but if you don't review your content, you could become less successful.
As speakers, we all know that engaging an audience is key, since if they aren't listening, it doesn't matter what you say. If you make references to popular culture, try to find more contemporary examples that make the same point. For example, I heard a speaker talk recently about how difficult it is to "set a timer on a VCR". Fewer and fewer of your audience will know what a VCR is (it was a video cassette recorder, by the way), let alone why it is difficult to set it.
Don't throw away all your good stories just because they are a few years old. However, make sure that you use vocabulary and examples that your audience understands. Otherwise, people will start telling stories about you, and "how good you used to be".
All good speakers continually hone their speeches, adding, subtracting and refining stories and anecdotes. However, there are dangers in changing a speech that works well, since you could ruin it for the audience (and you're not being paid to use them to experiment on).
So, if you want to make changes to a story, keep the rest of the speech the same. If you want to add a new story, put it between two stories that work really well. After your revised speech, note down what worked and what didn't. Keep your speeches fresh by continually improving your material. But make sure you keep the good stuff in. | 
