the pinking blades are not (sharpen-able) what are you using yours for to dull it so quickly? i've had the same blade in one of my cutters for about 4 years- it's still pretty sharp.
prehaps you should invest in a good pair of pinking shears---they can be sharpened and will last for many many years- i own my great grandmother's-and she passed away over 50 years ago. they are great shears!