The pair from Victoria, B.C., got off to a strong start, holding their position behind the American team of Kristin Hedstrom and Julie Nichols with a sprint towards the finish line.
"Obviously we wanted to go out and win the repechage, but what we have to take home with us is recognizing that as we are moving through the regatta we are improving immensely," Jennerich said.
"The semi is going to be an extremely tough race. We will have to race that semi like it's a final."
Cuba's Yaima Falcon Velazquez and Yoslaine Dominiguez challenged the Canadians late in the race, placing third and also advancing to Thursday's semifinal.
Men's double fades
The lightweight men's double of Doug Vandor and Morgan Jarvis failed to advance out of their repechage round.
The Canadian pair held a comfortable lead at the start of the race but could not hold off charges by Greece, Hungary and Australia.
Vandor of Dewittville, QC, and Jarvis of Clearwater Bay, Ont., dropped out of medal contention with a fourth place finish and will instead compete in semifinal C/D on Wednesday.
Also at Eton Dorney, the Netherlands, Romania, Australia and Great Britain will join Canada in the women's eight final after taking the top four spots in the repechage.
Canada and the United States were the fastest in their heats Sunday and advanced directly to Thursday's final.
Germany placed fifth in the repechage and did not advance.
In the men's double sculls, Canadian duo Kevin Kowalyk and Michael Braithwaite placed last in their semifinal race and did not make the final.