Even if the revived individual is presumed to be the same as the deceased individual, rather than a clone or twin/sibling — for example, if a unique "soul" energy signature carrying memories was discovered, which only settles into the body if a "live" copy didn't already exist — then this will vary by jurisdiction.
Currently, the closest scenario we have access to is presumption of death, where a missing individual is ruled as legally dead. For example, in the UK a request can be made to the High Court if, after 7 years, there is no evidence that they are alive, the people most likely to have heard from them have had no contact, and inquiries and searches made to try and locate the individual have all failed. Their estate then undergoes probate, and the individual is not entitled to compensation should they subsequently resurface.
In the USA, declaration of death is at a state level, unless there is specific cause for the federal government to have jurisdiction (e.g. military personnel, missing in combat). Criteria evaluated commonly include
- The party normally must have been missing from their home or usual residence for an extended period, most commonly seven years
- Their absence must have been continuous and inexplicable (e.g. the person did not say they had found a new job and were moving far away)
- There must have been no communication from the party with those people most likely to hear from them during the period the person has been missing
- There must have been a diligent but unsuccessful search for the person and/or diligent but unsuccessful inquiry into their whereabouts.
Most states require an absence of 7 years, but some require fewer (Minnesota and Georgia have both reduced it to four!). Many states will waive this time period under exceptional circumstances such as "imminent peril", for example a plane crash. This was used in the aftermath of 9/11, to issue death certificates for numerous missing individuals.
Some states will require that the individual be compensated should they return, while others make no such provision.
A word of caution
In 1976, a man named John Burney disappeared in Arkansas, and was declared legally dead after the state's required 5 years had elapsed. In 1982, he resurfaced, and attempted to reclaim his estate. The courts disagreed, and declared that his beneficiaries did not have to return the money. On the other hand, the company who had paid out life insurance to his wife and company sued — and won. John Burney wound up owing them $470,000.