Repond was born on 18 October 2006 in Basel, Switzerland, to father René, a management consultant, and mother Claudia, a lawyer.

[4] Repond made her international and ISU Junior Grand Prix debut at the 2021 JGP Slovakia in September, coached by her older sister Jérômie.

She competed at three more international junior B events in the fall, taking the title at both the 2021 Trophée Métropole Nice[6] and the 2021 NRW Trophy,[7] and placing second at the 2021 Santa Claus Cup behind Nina Pinzarrone of Belgium.

Doctors discovered a partial fracture in her foot days before the competition but she still decided to skate to qualify for the European Championships.

With reigning national champion Alexia Paganini absent, Repond was heavily favored to win the title.

At the European Championships, held in Espoo in late January, Repond placed third in the short program despite a quarter call on her triple Lutz jump, behind Georgian segment leader Anastasiia Gubanova and pre-event favourite Loena Hendrickx of Belgium.

Her placement marked the first podium finish for a Swiss women's singles skater at the European Championships since Sarah Meier won the title in 2011.

[16][17] Repond was next assigned to the 2023 World Junior Championships in Calgary, where she aimed to finish in the top eight and thereby qualify a Swiss berth at the 2024 Winter Youth Olympics.

She placed third in the short program despite a fall on her solo triple lutz, and later rose to first in the free skate to finish second overall behind Isabeau Levito.

[11] She finished seventh at the 2024 European Championships, and said afterward she felt "a bit disappointed," speculating that she had nerve issues due to limited training time while recovering from her hip problem.

"[24] In June, Repond announced that she had relocated to Oberstdorf, Germany to train under Michael Huth while simultaneously continuing to be coached by her sister, Jérômie, in Basel.

Due to the event being a close competition, Repond finished only 0.30 points behind bronze medalist Hana Yoshida.

"[26] Shortly before her second Grand Prix event, the 2024 Cup of China, one of Repond's skating boots broke, though she was able to compete by taping it.