Large cat trees generally do not need to be replaced very often. If you choose a sturdy large cat tree made of durable materials, you can probably expect it to last for several years of use. Keep an eye out for any wear like ripped fabric or unraveling sisal that may pose a hazard to your cat. Be sure to replace your large cat tree whenever you notice hazardous damage, or just replace it when it starts to show unsightly signs of wear.