A person who makes a will (a testator) may update or revise the will at any time during their lifetime if the testator has the required mental capacity (is of sound mind) and the document is executed or signed with the required formalities (such as witnesses and signatures), as provided by the state’s laws.

There are generally two ways to update a will—execute a new will (usually the best option) with the required witnesses, signatures, and other formalities—or execute a codicil (a supplement to an earlier will), with the required witnesses, signatures, and other formalities, as provided by the state’s laws.

Laws regarding the use of codicils and the required formalities for wills and codicils vary from state to state and are usually located in a state’s statutes—often in the estates code or probate code.

A testator who updates their will by executing a new will should usually destroy the previous will to avoid questions regarding which will reflects the testator’s true intent and to avoid competing wills being offered for probate (recognition by the court).

In Nevada, a testator has the right to update or revise their will at any time as long as they have the mental capacity to do so and adhere to the state's legal formalities. To update a will, the testator can either create a new will or add a codicil to the existing will. Both methods require the observance of specific formalities, such as obtaining the necessary witness signatures. Nevada law typically requires that a will be signed by the testator and by at least two witnesses who are present at the same time and observe the testator signing. When a new will is executed, it is advisable for the testator to destroy any previous versions to prevent confusion and ensure that the most recent will represents their true intentions. This action helps to avoid potential disputes during the probate process, where the court recognizes the valid will. The relevant statutes governing wills and codicils in Nevada can be found in the Nevada Revised Statutes (NRS), particularly in the sections pertaining to estates, trusts, and probate law.