Spyderco Sharpmaker does the job for me. 👍
I've found that it's much easier to do a light touch up more frequently than to sharpen something really blunt. I use a Sharpmaker, and a few strokes on the ceramic rods will usually bring a blade back to shaving.
Yes!... A knifemaker once told me that the best way to sharpen a knife is to never let it get dull. A few proper swipes on ceramic rods every few uses of the knife and you'll never have a dull knife again.