Ardern said National had failed to meet the target because it had focused too much on swabbing children and not enough on affordable, warm, dry housing.
"We will never deal with rheumatic fever until we deal with overcrowded housing and the inability of families to keep their homes warm and dry."
Labour wants to introduce stricter minimum standards for heating and insulation in rental properties. It would also provide grants to help low-income families with power bills over the winter months.
The National-led Government set a goal of reducing the rheumatic fever rate from four cases per 100,000 people to 1.4 cases per 100,000 people by mid-2017.
The rate hit a low of 2.4 cases per 100,000 people in mid-2015, but has since risen again to 3.4 cases per 100,000 people.