Unfortunately, replacement blades are not available due to safety reasons.
If you're experiencing dullness with the blade, here are a few things to keep in mind.
If colored pencils were sharpened, sometimes the lead can deposit a waxy buildup. If you sharpen a series of regular no. 2 pencils, the graphite lead and wood shavings of this type can at times help to remove some buildup.
While this may not definitely resolve a dullness issue, we hope that this suggestion might assist with improving performance.