"Why are you not cleaning the kitchen?"
Translation:Dlaczego nie sprzątasz w kuchni?
The first one is either "Sprzątam kuchnię" or "Sprzątam w kuchni", and the second... I'd definitely just say "Sprzątam lodówkę/w lodówce" without mentioning the kitchen at all. And if for some reason the kitchen is really important (but where else would you have your fridge? maybe in the cellar sometimes, but that's probably not the main fridge) then I guess I can add "w kuchni" at the end.