Next up for Joe Schmidt's side is the visit of Warren Gatland's Wales to the Aviva Stadium in Dublin on Saturday.
And the 30-year-old Heaslip, who started two of the three Tests Down Under for the Lions this summer, knows that the defending two-time champions will be a step up for the Men in Green.
"Huge improvements will be needed for next week," said 61-cap Heaslip.
"Joe (Schmidt) had a couple of choice words for us in the changing rooms afterwards, and I'm sure there will be more.
"It will be a huge challenge to go up against a team that's won this Championship two years in a row."