The 37-year-old became a dad for the first time when Mazza gave birth to their daughter Gia, now nine months, in September 2010.
He admitted that they are already planning their second child despite Gia's first birthday being a few months away.
Lopez said to Us Weekly: 'Yeah, we're always thinking [about baby number two]. We're practising, so we'll see!'
Mazza added that their daughter is already 'way ahead of her game' and is 'about to walk'.
Lopez said: 'She is sassy! She is getting a lot sassier and is getting a lot more vocal.'