If a valid will was made while you were living in another state, it is probably valid in your new state. However, many state courts require re-verification from the original will witnesses in person, to attest to the will's validity. Because of the expenses involved in finding your witnesses, it is probably best to rewrite your will after moving to another state.
A self-proved will avoids this problem by including an affidavit, notarized and signed by the will's witnesses attesting to the validity of the will.
Most states allow a will to be self-proved. The LegalZoom will contains a self-proving affidavit. If you move to another state, the will would likely be valid without the expense of tracking down witnesses.
Please note: self-proving affidavits are not valid in District of Columbia, Maryland, Ohio, or Vermont. In California, there is no requirement for a self-proving affidavit so wills are considered 'proved' upon proper execution.
