Hi Andrea, I imagine your cordyline's got pretty big in 12 years. You sould'nt have too much trouble in finding a replacement pot or planter in one of the larger garden centres, that carry a good selection, I'd go for one thats about 4" wider than the old one, add some broken crocks in the bottom to assist drainage.
Choose a good general purpose potting compost, cover the crocks with a few inches then center your cordy so that it's upright in the new pot ( make sure you dont allow the roots to dry out while your preparing the new pot, keep it covered if in doubt) If it's become root-bound gently tease out the roots with your fingers. Pack the compost in to avoid any air pockets but not too firm.
Water it in well and give it a feed of slow release fertilizer after about 6 weeks. Good Luck. Tbird+