I lost my pin during prefs one year. It's no big deal. There were a quite a few girls in my chapter that lost their pins and had to buy knew ones. It stinks when you have to pay that money all over again while you're on a college budget.
Your new member coordinator should be able to order you a new pin. I asked our's and I had my pin a few weeks later. The only thing is that you'll be pin-less during meetings until your order comes in.