Latu was the most accurate shooter in this year's ANZ Championship (94.3 per cent), although the Mystics finished a disappointing seventh.
"Cat finished the season strongly and showed improved connections and progress in her physical testing," Mystics coach Debbie Fuller said.
"International goal shooters have a tough ask because they need to keep growing their game while playing to their strengths. Cat is always looking for the edge or something new to add, while also being very grounded."
As well as Latu and Tutaia, the Mystics have also re-signed young defender Temalisi Fakahokotau for next year.