Is there a statute of limitations on how far back you can go to repeal/reverse/undo? Can it go all the way back to a country's inception?

We know PET plans to repeal everything Obama has done. Why stop there? Why not repeal women's right to vote? Bring back slavery? With a vanilla government  it can theoretically be effected, right? Is there anything that is sacrosanct and cannot be touched by even the most vile/evil person(s) or is everything on the table?