Progression looked well within her grasp with a 9.89-point heat total and her closest rival Sara Wakita (Japan) falling on her last wave with 50 seconds to go, but Japan eventually went 1-2-3 in the heat.
Vette now switches her attention back to the WSL World Qualifying Series with the final female events being played out in Australia at the end of the month.
The New Zealand team finished in 14th place overall, two places lower than their 2018 campaign.
Hosts USA won the team contest, Hawaii were second, Japan third and Spain fourth.
New Zealand results from Day 8 of the championships:
Under-18 girls, Repechage Round 9: Sara Wakita, JPN, 16.43, 1; Saffi Vette, NZL, 11.67, 2; Sanoa Olin, CAN, 7.77, 3; Nyxie Ryan, AUS, 5.76, 4.
Repechage Round 10: Minami Nonaka, JPN, 16.83, 1; Sara Wakita, JPN, 8.84, 2; Shino Matsuda, JPN, 7.93, 3; Saffi Vette, NZL, 5.93, 4.
U18 boys: Dimitri Poulos, USA, 15.33, 1; Alan Cleland, MEX, 13.23, 2; Tommy Coleman, USA, 12.1, 3; Joh Azuchi, JPN, 9.97, 4; Caleb Cutmore (NZL), 17th; Jack Lee (NZL), 21st; Luke Griffin (NZL), 65th.
U16 boys: Jackson Bunch, HAW, 17, 1; Taj Lindblad , USA, 10.53, 2; Afonso Antunes, POR, 10.5, 3; Ryan Huckabee, USA, 9.46, 4; Jayden Willoughby (NZL), 41st; Tom Butland (NZL), 41st; Tom Robinson (NZL), 65th.
U18 girls: Gabriela Bryan, HAW, 14.07, 1; Minami Nonaka, JPN, 11.53, 2; Noah Lia Klapp, GER, 6.66, 3; Sara Wakita, JPN, 5.23, 4; Saffi Vette (NZL), 6th; Estella Hungerford (NZL), 37th; Georgia Wedrell (NZL), 73rd.
U16 girls: Noah Lia Klapp, GER, 11.34, 1; Zoe Benedetto, USA, 10.97, 2; Betty Lou Sakura Johnson, HAW, 9.93, 3; Caity Simmers, USA, 8.16, 4; Brie Bennett (NZL), 25th; Ava Henderson (NZL), 31st; Natasha Gouldsbury (NZL), 43rd.
Team results: USA 1; Hawaii 2; Japan 3; Spain 4; France 5; Australia 6; Portugal 7; Germany 8; South Africa 9; Canada 10; Brazil 11; Peru 12; Costa Rica 13; New Zealand 14; Argentina 15.