your best bet is to use a shine spray on dry, styled hair...try not to use too much hairspray either, it seems to make hair dull...
depending on what colour your hair is, you could always change it (ie if it is blond and damaged, try something a bit darker in a semi permanent that would add some glossy shine...)
my hair was horribly damaged about two years ago from constant highlights and its finally healthy again, i started only shampooing 2-3x a week at most, wearing my hair up the rest of the time, do a good hair mask about once a week to add strength back in your hair as well. use gentle, sulphate free shampoos, and dont heat style too much.
try biolage shine spray, it was by far my favourite of all the ones i tried, it also seemed to work to protect my hair from my flatiron. one last thing, even if you are trying to grow your hair, make sure you get regular trims to keep it healthy! good luck