Depends on your age. Also, depends on how long you have been back together. People fantisize about past lovers, they romanticize how it really was. The sun was always brighter, the skies were always bluer, and the music was always sweeter.
Wait until you have your first major disagreement, or first crisis situation come up, or your first sickness. Take time to really get to know her now, not 8 years past, and see where she is at, where she is going, and see if that fits for you.