The literal meaning, "wants to know it again", does not fit the context.
What does the phrase mean?
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Closest might be „meet a challenge once again“. If for example German chancellor Angela Merkel is applying for chancelorship again after 2 terms of office the papers might write „Sie will es noch einmal wissen“. It includes the question: Am I still good enough to make it? (That's what she wants to find out.) However it actually isn't used if you really doubt it.