Restaining wood without sanding is possible, but it is generally not recommended for optimal results. Sanding helps to create a smooth and even surface by removing any existing finish or stain, allowing the new stain to penetrate the wood effectively. Without sanding, the new stain may not adhere well or produce desirable results. However, there are alternative methods such as using chemical strippers or gel stains that can help achieve some level of restaining without extensive sanding.