hair glaze

I had my hair dyed jet black last year in late August or September.  It is now looking dull and I'm not sure if I need to dye it over again or try a clear glaze or something.  I heard Redken EQ is a good glaze but I go to a domician shop and I don't think my beautician uses that brand.  Is there a certain brand I should use? Should I use a glaze or is it time for a dye again? I'm not sure which to do or is appropriate, don't want to dye it and it still be dull looking. don't know it its time for another dying or if its just my hair and its dull. It's still dark black but little strands of grey are showing and in the sun I can see a little of my brown coming through. Can someone please give me advice or suggestions before I go to my hair appointment this week??

Okay thank you, that seems right.  I'm going to ask the lady that does my hair when I go in tomorrow. I remember though just a few weeks ago or last month I asked her was it time for another dye job and she was like no but I'm like "you don't see little strands of grey coming through and some brown??" I guess i'm going to just have to tell her what I want and do it.  But is doing a dye and a glaze at the same time safe for your hair? it's not too much for it? or were you meaning to get it dyed then glazed another time?

Okay thank you very much............ On a different note, im having a problem uploading a picture on here as my avator. After i do it, an error message keeps coming up saying the email i used has been blocked by the administrator or use another domain but my email seems to be okay because i get notifications to let me know when reponses have been posted. dont know??