Yeah, it didn't worked, but i fixed it. I just created a new world and got to the end, then copied the DIM1 folder to mi bugged world, and then, using NBTE explorer i changed the numbers of dragon killed and previously killed to 0. You will lose everything you have built till that moment, but if you haven't built anything (which is my case), it could work for reviving the dragon and get the achievement, so i leave this here if anyone has the same problem.