DEAR MISS MANNERS: When hosting a cocktail hour, how does the hostess gracefully navigate the quantity of food served? For example, if the cheese platter is reduced to a few bits, should the hostess be constantly monitoring and replenishing as necessary (even if the “hour” is approaching or has passed)? I certainly don’t want to appear stingy with guests. But the idea of bringing out more food seems to encourage lingering and drifting into the dinner hour and beyond. Also, what is an appropriate answer to a guest who inquires, “Is there more cheese/crackers/dip …?” I was taught that, as a gu…