When an old woman wakes up in the spirit world realizing about her death and finds out she has only 80 minutes left to take rebirth, to correct her karma in the newborn life, she must complete a series of tasks or risk a new life of struggle and trials.

Your protagonist is the ghost of an old woman. The goal is too vague – she must struggle to do a series of tasks. In a broad sense, that’s what every movie ever made has been about. What specifically must she do to atone for her sins on earth?

The stakes are that she may be reincarnated to a life of struggling and trials … suggesting that your character lives in a universe where everything is pre-determined. Which causes a logic problem for me in your story. If it’s a story about a character trying to do a bunch of good deeds so that she is given a BETTER life, which is devoid of free will … is it really her fault that in the previous life which was devoid of free will, that she did things that she must now atone for? It wasn’t really her choosing to life incorrectly, was it?

What if, instead of the threat of a life of struggles, you instead borrow from the idea of Hindu reincarnation, and she’s reincarnated somewhere further down the list of beings. Perhaps she will return as a beetle, or a worm, or something like that.

The hook, as you described it on a previous version of the logline, is that she ages backwards, 1 minute for every year of her life, until she reverts to the moment of conception, and is suddenly transported back into the real world. That is an interesting time clock to put on your character, and I would suggest trying to include it in your logline, because I’ve seen stories about ghosts trying to atone for their sins before, but I haven’t seen that trope mixed with a ‘Benjamin Button’ that plays out in real time, and for that you’d get my ticket money.