The Scottish champions lost the first leg at Ibrox 1-0 last week and will have to win in Sweden to have any chance of progressing through to the group stage.
"We have to put right what went wrong in the game last week," said 27-year-old Whittaker.
"We know we weren't at it in the first leg and we are determined to put it right this time. We need to score goals to go through."
Rangers secured their first win of the season on Saturday, defeating St Johnstone 2-0.