Complex sentence: She retained her world title and set the world record time in partnership with Heather Stanning at the 2014 World Rowing Championships in Amsterdam, and they retained their World title at the 2015 World Rowing Championships in Lac d'Aiguebelette, France.
Split into simpler sentences: She retained her world title and set the world record time in partnership with Heather Stanning at the 2014 World Rowing Championships in Amsterdam. They retained their World title at the 2015 World Rowing Championships in Lac d'Aiguebelette, France.