turn over a new leaf

Figurative by the same metaphor as with turn the page.

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turn over a new leaf (third-person singular simple present turns over a new leaf, present participle turning over a new leaf, simple past and past participle turned over a new leaf)

1. (idiomatic) To engage in self-improvement; to begin a good habit or shed a bad habit.

   Every year he resolves to turn over a new leaf and start exercising.

• start with a clean sheet
• turn the page

• (antonym(s) of “determination to do what is wrong or destructive”): break bad

• get one's act together
• wipe the slate clean

• “turn over a new leaf”, in Cambridge English Dictionary, Cambridge, Cambridgeshire: Cambridge University Press, 1999–present.
• “turn over a new leaf” in Longman Dictionary of Contemporary English, Longman.
• “turn over a new leaf” (US) / “turn over a new leaf” (UK) in Macmillan English Dictionary.