Yes, but if they mobilize to the maximum possible extent they might be able to field up to a thousand troops. Of course, those would be the crack Liechtenstein soldiers, trained from the start of the war to the highest excellence possible in such a grand country. So I would guess that they wouldn't add more than the defeat of all enemies to the war.
But, should their contribution miraculously fail to influence the war, I could see the country's distinguished history ending at the war, the prince would be deposed and the country might see itself added to Austria or Switzerland. The only way it could stay independent would be because the Entente decides that they don't want to rewards Austria for being their enemy in the war, or Switzerland for doing absolutely nothing at all.