Re-did means doing something again or making changes to it. The antonym of re-did is "left alone" or "did not change". When you left something alone, you did not do anything to alter it. You just let it be as it is. In terms of a project, if you left it alone, you did not make any revisions or changes to it. Therefore, the antonym of re-did would mean that there was no need to go back and revise or change anything as it was satisfactory the first time it was done, implying a level of efficiency and success.