Why we have Deja Vu:
Many believe that after death we go to a higher place (no pun intended), or if you live your life bad you go to hell.
I don't believe in either.
I believe that when we die, we automatically reset and our lives start over. This means we're able to re-do things that we may have not done before in our previous chance at that life.
And if we choose to do the same, it will result in Deja Vu.