The Dons are striving to reach the Championship via the play-offs for the third time in four years.
Their previous two attempts have both been halted at the semi-final stage, defeated on penalties by Scunthorpe in 2009 and losing 4-3 on aggregate to Peterborough last year.
The Posh loss in particular was a bitter pill to swallow, with the Dons upset at decisions which went against them over the two legs.
But Lewington is adamant that any sense of injustice is out of the squad's system as they prepare to face Huddersfield at stadium:mk.
"At the time it was difficult because there was a sense of injustice and it stayed with us through to pre-season," said the left-back.
"But this year has been a fantastic campaign and if there was any side effects it would have shown before now.
"The past is the past, you take the good bits out of it and leave everything else behind.
"We can learn from where we went wrong last year and try and put it right this time round."
A surprise home defeat to Walsall on the final day of the regular season means the Dons must play the crucial second leg at Huddersfield, but Lewington is unfazed by the prospect.
"It seems much has been made of this but we are very comfortable away from home," said the 27-year-old.
"We have shown that we are a good counter-attacking team so we are not losing any sleep over it.
"Taking a lead into the second leg would be the best outcome, a draw would be par for the course and even a one-goal deficit would not be the end of the world.
"As long as you are still in the tie when the second game comes round then any outcome is possible."
Huddersfield manager Simon Grayson is no stranger to the play-offs and is already feeling the buzz ahead of today's game.
The 42-year-old was involved in the play-offs four times as a Leicester player, as well as guiding Blackpool to the Championship at the expense of Yeovil in 2007 and overseeing Leeds' semi-final exit to Millwall in 2009.
"I think the play-offs are a brilliant idea," he said. "I was at Leeds as a player when they did the first one (in 1987) and although that was a different set-up it gives the players something extra to play for.
"It can end in doom which I have experienced, but I have also experienced the winning feeling.
"It gives a buzz for the supporters at the end of the season."