Just because you receive a prompt to write a review doesn't mean you're obligated to leave one. It looks good for both hosts and guests to have repeat stays on their review page, if those reviews are good, because it shows that the place is worth coming back to and that the guest isn't just on good behavior the first time they stay, but is always a welcome guest. However, more than a couple of these is pointlessly time-consuming, so as Emiel says, just ignore it.