Since you're brewing extract beers, you don't really have any control over how fermentable the wort is. So to change your attenuation, using a different yeast strain is pretty much your only option. If you want to continue with dry yeast for now, try the S04 strain.
But there are other things to be aware of in switching strains - it's not like the beer will taste exactly the same except with less alcohol. A little less attenuation also can translate to a heavier mouthfeel, a little extra sweetness, and/or more perceived maltiness. Frequently some of the less attenuative strains also produce more esters and other compounds so you'll have a generally more flavorful beer. None of these things is necessarily bad or good - just personal preference.
I use a less attenuative strain in all my beers because I like these characteristics, but most people on HBT like to get VERY high attenuation. People here are afraid of sweetness in their beers because they believe them to be less drinkable. I can sympathize with that, but I still choose my malt-bombs over watered-down, bland California ale yeast.