You only deserve to win the audition if your average performance is good enough. Imagine the converse: your peak performance was in the audition, and your actual performance in the position never lives up to the expectations of the position. So, don’t do your best. Do your normal, which doesn’t require any particular or special preparation.

There’s a second trick. As long as you continue to improve, you will succeed at each successive audition. It’s only a matter of time until even a substantially below-average performance exceeds the threshold.

There’s a third trick. You don’t really need the audition. It’s fine if you fail. You got this far without it, you can probably go at least as far again without it.

Because your average performance should be good enough, it should not be particularly surprising to succeed, which means it shouldn’t be particularly exciting. If the idea of winning the audition is exciting, then you’re probably not good enough yet. (It might instead be a bug in your reasoning.)