It depends. If you’re noticing your home is very drafty or exceptionally noisy, it may be time to update that insulation. If you’re seeing urine stains or pest droppings, those can create animal-caused bacterial and fungal pathogens and their urine can cause mold. All of that can become airborne, eventually traveling into the main living areas of your home making you and your family sick. Don’t miss out on the state rebates on insulation before replacing! Do your homework.