Clover is a tough one. But you said you got rid of a lot of it last year. What did you do then? "Nature abhors a vacuum" if you left all that soil bare, then for sure some weed was going to fill it in. Once you get rid of the clover, MULCH HEAVILY to prevent it from coming back.
Also the clover thrives in low-fertility soils. It has the ability to pull nitrogen from the air, so it doesn't care if there's any in the soil. Making sure your soil is very fertile, helps the plants that you want to be there thrive and out compete the clover.
Corn gluten meal is a weed seed suppresser. It won't do anything to the clover that is already there, but if you put it down in August or so, it will keep any weed seeds (or flower seeds!) from sprouting. Then do it again in early spring.
Otherwise, keep pulling! The compensation is that all that pulled clover is wonderful stuff for your compost pile!