Straightning your hair? duller?

ok so i have red hair and its curly and thick and i just got it cut for locks of love so now it is either straight or puffy and ewww so i have to whereas when it was longer it was ok cuz it didnt puff out. Now tho since i have been straightning it every day my hair is dull. is it just the winter? can straightning it make it dull? i wouldnt care but red hair is rare and i like it and now it barely looks red and i want the redness backk. and if it is can you help me with some kind of shampoo and conditioner to restore my hair color?