Upvote:5
The concept of passport renewals in Italy was abolished and doesn't exist anymore. What happens now is that you get a brand new passport with a ten-year validity from the date of issue. Quoting from the Italian Police website:
Il passaporto è rilasciato ai cittadini italiani e ha durata decennale. Alla scadenza della validità, riportata all'interno del documento, non si rinnova ma si deve richiedere l'emissione di un nuovo passaporto.
See my other answer on the topic for more details.
Having said this, you can obtain a new Italian passport at any moment you wish, regardless of the expiry date.