Water Chem. ... sulfate, carbonate, iron, and many other minerals
Grain Bill ... some grain flavors linger, others are more crisp (carmel vs pilsner malt for example) Also, If you are using a lot of types of grain in a single recipe, try backing it off to two or three grain types only.
Hops ... oil content/ratio of Humulone, Cohumulone, Adhumulone, lupulone, essential oils, etc can vary among types, some are crisper, others less so.
Each one has an effect and can add crispness or leave a little more weight on the palate.
Sometimes, just adding some sugar in place of malt (keeping the same OG, though) will lighten a beer and make it crisper.
I have done each of these to tune a beer to make it lighter and/or crisper on the palat.