"Let's do this well this time."
Translation:이번에는 잘 하자.
I'm not sure that I understand your question. 잘 하자 Is "let's do (it, this, that: depending on the context) well". 이번 is "this time". 에는 is a contraction from the markers for time 에 (at) and subject (는), which gives more focus on it.