To dream of a deceased loved one coming back to life is very common especially soon after their death. It means you have not yet fully accepted their death. These dreams taper of as time goes on.

To dream of someone who died a long time ago coming back to life or anyother character in your dream that died and is coming back to life means there is something in your own life that you are trying to resurrect such as a dying relationship, a failing project or perhaps a personal skill or ability of your own that you seem to have lost touch with.