I know things get spilled, but when you do make sure you clean it up.
I don't mind if you make a mess sometimes, but I'd like you to clean up after yourself when you do.
ーI know things get spilled, but when you do make sure you clean it up.
「こぼれるのは仕方ないけど、こぼしたらちゃんと片付けて。」
I know things get spilled で（ものが）こぼれるのは仕方ない、というニュアンスです。
clean up で「片付ける・きれいに掃除する」
ーI don't mind if you make a mess sometimes, but I'd like you to clean up after yourself when you do.
「時々散らかすのはいいけど、ちゃんと自分で片付けて。」
make a mess で「散らかす・汚す」
ご参考まで！
Spilling the drink can't be helped but just clean it please.
Children always spill food or drink and they leave it as it is.
ご質問ありがとうございます。
"(food, drinkを) こぼすのは仕方ないけど、片付けて"は英語で「Spilling the drink can't be helped but just clean it please.」と言います。
こぼす＝spill, drop
～仕方ない＝～can't be helped
「Children always spill food or drink and they leave it as it is.」＝「子供たちはいつも食べ物や飲み物をこぼし、放置してる。」
ご参考になれば幸いです。
カナダ 
トルコ 
