How can I improve my story (title)?

Explain the story more simply. A good story can be summed up in one sentence, which is your logline. From there, get a title that can sum up that logline, or morever tell the audience what your entire plot is about in the simplest terms possible. Maybe it's just one word, maybe it's a character's name. You used the word "Existence" in your summary and I think that would make a great title especially since your story seems to deal a lot with death, revival, souls, etc...the word Existence sums up all of those things. Just an idea though :)