Snackbar ideas/concession stand ideas?

i work at a small snack bar during the adult softball games from 6-9pm. we have been having some bad money problem; the employees are making more than the actual snack bar is and we've been losing alot of money. we've got plenty of things; hot dogs, nachos, popsicles, tons of candy, sodas, few energy drinks, iced teas, and just recently began a grill where me make sliders. and the prices seem decent. but business is still so slow. any suggestions with marketing or just any other products that would sell well? we're low on cash so can't be too pricey but really any suggestions would be great. thanks!