Hi Murphy,
You can try the old sandpaper trick. Using 220 to 80 grit sandpaper cut through the paper several times. If this doesn't work, it's time to send them to a professional sharpener.
You might consider purchasing a rotary cutter with a pinking or a wave blade such as the KAI 45MM Rotary Cutter. KAI's blades are made of very sharp high tungsten steel. I sure that the other major rotary manufacturers also offer these same blades too, and you can purchase them at a number of retailers . I know first hand that sales of pinking shears are down considerably due to the popularity rotary cutters.