It requires flawless, efficient logistics to keep the latest styles on the racks, and it means attracting fickle teens to shop its stores. J.C. Penney's trackrecord doing that has been less than stellar, and few teens are likely to be convinced it is a cool, hip place to shop. Because it's only a single private-label brand, and not a complete remodel like Abecrombie and Gap are proposing, J.C. Penney's risk is seemingly limited but it does suggest the retailer still wants to tinker with its successful turnaround efforts, and that alone may be the biggest hurdle it has to surmount.