Renewal Vows is nothing about legal paperwork or religious procession. It is mostly made by married couple to strengthen their commitment even more by re-pronouncing it in a special occasion like anniversary.
Being an unofficial procession, vow renewal is normally led by Priest of the corresponding religion. In addition to re-pronouncing the vow in the couple’s own words, the procession also includes blessing and prayer for safety, health, prosperity, happiness, and eternal togetherness. No documents required, no certificate issued. Included are fee to invite priest from corresponding religion, and donation to the church/temple of corresponding religion.