Explain what you used in making your mead. Just honey, water and yeast? What yeast did you use? How large is your batch size? What was your O.G.? How long has it been since your yeast pitch, i.e., has your mead aged long enough?
If the yeast strain you used has a low alcohol tolerance you can always add step additions of honey (like 8-12 oz. honey per gallon) to raise the S.G. 5-10 points and see if it stabilizes over time at a higher S.G. by virtue of the yeast giving up. If you used a Champagne yeast your resulting alcohol levels will be probably higher than you want, they don't give up.
The classic way to do it is rack onto some potassium metabisulfite (crushed Campden tablets - 1 per gallon) and potassium sorbate (1/2 tsp per gallon) dissolved thoroughly in water or in a cup or two of the mead. Then stir the mead with a sanitized rod or dowel gently but thoroughly. But then again many people prefer not to use any chemicals, some sense the taste sorbate imparts and some people are allergic to them. Now I assume you don't happen to have a 0.5 micron filter to filter the yeast out of your mead. Given that, another option is cold crashing the mead. The mead may be cold stabilized at 30-32 degrees F, for 3-4 weeks. This will kill all popular strains of yeast. If you cannot reliably reduce your wine to this temperature range for an extended period, you may need to chemically stabilize it.
So let's assume you have the mead stable so it's not going to continue fermenting. Then, take a measured sample of the mead, like a cup and slowly start to stir in the honey a little bit at a time, until you reach the desired sweetness to your taste. Calculate how much mead you have, and multiply the amount of honey to reach the same sweetness for the full batch. Carefully stir it in to avoid oxidation, then let it sit for a couple of months to make sure fermentation has not restarted. Then you can bottle and age in the bottle.