My guess is that after all the remaining activity in our brain ceases, time just passes to us instantaneously since we're not conscious and can't actively sense the passage of time. If the universe just expands into entropy and nothing else happens, then all the time after death is just an unconscious, dreamless sleep.
But if the universe does crunch and reform and re-create itself over and over again like some physicists hypothesize, then it's only a matter of time before events happen that once again lead to the formation of that underlying, chemical organization within your brain that defines who 'you' are and never changes from your early infancy to your death. Then you're just 'back', I guess, hopefully living a life that isn't outright identical to the one you just finished.
Don't take any of this seriously though. I'm an 18-year-old living in the 21st century with a hopelessly small understanding of how the birth/death of the universe happens in its entirety, or how countless biologically-similar cells clustered together into a 3lb lump can create consciousness. My guess is based on the worst quality of evidence imaginable.
