Yeah a misting spray bottle may work. I know they sell some solutions that do the same thing or actually turn the color of blood to something brighter. I also think there's a lamp (UV?) that will cause blood to glow. Try looking in Cabela's or some other outfitter for similar products. Or buy and train a dog to track for you, or hire these guys:
http://www.deersearch.org/
according to an article I just read a blue filter on a flashlight will cause blood to stand out. Don't know if that helps you any, but:
http://www.surefire.com/maxexp/main/co_disp/displ/carfnbr/247/sesent/00
Saw another product
http://www.xenopuselectronix.com/XeLED_BT.html
but it's pricey and uses a red beam so I doubt that'd help.