Sarah Katz purchased the lemonade at a West Philadelphia Panera in September 2022.
Her family believes she may have seen the "Charged" in the name of the drink as referring to electrolytes rather than caffeine.
Katz was diagnosed with LQTS when she was five years old, and managed symptoms by taking medication and limiting caffeine, the lawsuit stated.
The Charged Lemonades contained as much as 390 milligrams of caffeine, and Panera has since discontinued selling the drinks.
Panera is still facing other wrongful death lawsuits over the beverages. No financial terms of the settlement have been disclosed.