If you execute a living will and then change your mind and want to create a new living will, there are two things you can do. First, you can revoke the previous living will. A living will can be canceled or revoked at any time. You can cancel your living will by indicating, in writing, that it has been cancelled. Destroying your original living will may cancel the will, but revoking the will in writing is more formal.
Second, you can execute a new living will that expresses your current desires. This has the effect of canceling your previous living will. The revocation is effective when you (or someone else who witnessed your revocation) communicate it to your attending physician or healthcare provider.