Yes, you can. If a property comes down in price, the listing will be highlighted automatically and for free for a month. The drop will be shown both in the price (euros) and the percentage of price reduction. In addition, the price reduction will improve your listing’s position in the lists.
Be aware – there is a minimal price drop necessary for the listing to be highlighted and the price of the property must also be lower than it ever has been before. That is to say, if you raise the price and then lower it so that it is the same as or higher than the previous minimum, your listing will not be highlighted.