You can achieve that in different ways…
1st is to “cheat death” by preventing the cause of death. If you know the person is going to die in a specific way, use magick to keep them away from experiencing that event. If it’s an accident, you prevent/protect the person from it. If it’s a disease that they have, you heal it etc this is easy and anyone with enough experience can do it.
2nd, By the resurrection of the dead body. This can be done by keeping the body warm and “fresh” during the whole process and for as long as possible. Then use magick to “curse death” in a similar way of performing an exorcism, in the form of a prayer to the divine, or by directing energy from the practitioner to the dead body. Different traditions, different techniques. This method can and should be done with one or more people because it must be done non-stop until success. If the process stopped for any reason then you would need to start all over again. It could take a day, sometimes longer, making it sometimes difficult for one person to complete. IF the body started to decay, then there is a risk of resurrecting a zombie-like person. Bad idea. Also keep in mind that in this case, you’re not only fighting death, but you’re also working against the person’s will to die. If that’s what they want, you’ll have powerful resistance that would make it extremely difficult, if the operation succeeded the person would have deep depression and mental instability which may cause a lot of other negative impacts on his-her personality, so you won’t have the same exact person you used to know. This art is almost lost today but it does exist within very closed groups, usually very religious.
Spirits can be used for the 1st method directly. But they can’t help directly with the 2nd, as far as I know. With the 2nd method, spirits are used as intermediary powers between the dead, the practitioner, and the divine. But they can’t “do” anything themselves.