They should be separated throughout the year, and put together for breeding.
Generally, they don't have to be brumated. I do not brumate my reptiles. They have always done better for me by leaving them at a constant 90F throughout the year. If not done properly, brumation can lead to health problems.
Otherwise, the only thing that I can tell you is to separate them for a few weeks, and try again. I leave my males in with my females until I see signs of the female being gravid. Not everyone does that though; most breeders only leave the male in for a few hours.
Please, keep in mind that you need a proper incubator, and plenty of housing for hatchlings. Also keep in mind that it's not as easy to find homes for leopard geckos as you are 1) thinking and 2) hoping.