Staying on message is a delicate dance between saying what must be said while not sounding robotic. You want to sound conversational and interesting, not scripted and rehearsed.
One way to do that is to remember that a single thought can be expressed in more than one way. Repeating the message does not mean using the exact same words.
You need to become effective at restating your point without sounding like a broken record
For instance, your first response might be a statement expressing one of your talking points. A secondary response might include an example that you can use to explain why it's important. A third response might include a statistic to back up your point. Each time, you underscore your essential message or talking point.
The value of repetition lies in the fact that we don't all hear everything a speaker says the very first time or in the same way. Reporters and talk show hosts certainly don't. Also keep in mind that listeners and viewers might be joining a program in the middle of an interview and have missed everything you have said up until that point.
So, you need to become effective at restating your point without sounding like a broken record. The way to do that is to mix it up a little. Think through how you can emphasize your message using a variety of responses.