leatherjackets

last winter i had a massive leatherjacket problem, my lawns were stripped bare both front and back gardens, i treated the lawns with nemotodes in the spring and last month as well, the lawns have been re seeded in the spring and have grown back nicely, what i need to know is, will this be an on going problem and do i need to treat with nemotodes yearly? any advice would be great thanks.