I can only guess you're round about Washington way.
The story with alcohol levels and brew is all about the amount of sugar available to the yeast. The more simple sugars, the more the booze. (up to a point)
So you can totally take your regular recipe and add a little sugar to it (0.5-1.0 lb), boost the original gravity and your yeast, assuming it's generally healthy, will grant you more booze.
There's a cost though. Since regular old sugar pretty much ferments into nothingness, it also cuts the body of your beer. If you add too much sugar, you'd end up with something insipid, bland and tasting of harsh alcohol.
Assuming it ferments all the sugar, that is. If you add too much sugar the yeast will give up after a point and stop fermenting yielding that extra sweetness you were worried about. Oscar's advice is well taken - find a good high alcohol Extract recipe to start with and you'll be sure you'll end up with something intended to be a butt kicker and good tasting.
Also, make sure, as you go up in strength, you need healthier yeast to get the job done right. Read up on starters or throw more yeast into the beer to start with!