Australia earned an unassailable 2-0 lead in the three-match series after thrashing Sri Lanka by an innings and 201 runs inside three days at the Melbourne Cricket Ground.
"This is our standard now, we've got to continue to get better from here," he told reporters. "I think we need to be realistic as well - it's about consistency. It's nice we've done it in the first two Tests against Sri Lanka and it's great we've won the series, but we have a lot of work to do as a team."
Australia will aim to seal a 3-0 series whitewash when the final Test starts in Sydney next Thursday, after which they face Sri Lanka in five one-day internationals and two Twenty20s.
Clarke's men will then tour India in a four-Test series during February and March before the Ashes start in England in July.
Clarke praised his side's ruthlessness, which he confessed went missing in the recent 1-0 series loss to South Africa.
"I was really impressed with the way we kept Sri Lanka out of the match throughout the whole Test. That's something we will need to make a habit of going forward with some very important series coming up against firstly India and then the Ashes in England," he added.
"I don't think you develop (ruthlessness) overnight, I think like I say we've learnt from what happened against South Africa.
"Our aim is to repeat our effort here in Sydney and win the series 3-0. We've still got a lot of improvement to do as a team but it's a really positive step for this team to see that we are improving."