Sharpening a carbide tipped blade helps to retain the blade in good condition and working order. Prior to sharpening it, make sure to clean it properly. You can do this by letting it soak in a container full of warm water and some citrus oil soap. This will help to loosen away dirt and other residues found in the blade's teeth. Then, scrub the blade with a soft brush and wipe it dry.
Now you have to use a rotary tool designed for sharpening. Affix a wetted diamond paddle hone attachment to it. Then, wearing gloves, start moving along the teeth of the carbide tipped blade so as to sharpen it. Rinse the blade again when done and allow it to dry.