Even though she already knows how to speak, her speech is going to change, and quickly. Speech therapy m,ight be a good idea.
OP, have you considered a cochlear implant? Your daughter would likely be a very good candidate.
Not necessarily, maybe if she had starting losing her hearing when she was much younger, but 17 is pretty damn long time to have been hearing and speaking. My loss started at age 20 in one ear, 25 in the other. I'm 38, in one hear I'm profound to no response, and profound in the other. And I have been for at least 2 years, and for at least a year of that I was wearing aids meant for severe loss, so I basically heard complete gibberish for year and mostly speech read. I still rely heavily on speech reading but the more powerful ha's give me enough speech cues that it makes it easier. Anyway.....I have never had speech therapy, my voice and speech are fine, I haven't forgotten how to form letters etc etc. without my ha's in I can't hear myself, but unlike some posters I can still tell how loud I'm talking. Honestly I have know idea people can't tell they're yelling, I don't know, it's just an awareness of projection.
I wouldn't jump right into speech therapy, it seems like she's going through enough adjustments at school, if her speech starts deteriorating then put it on the table.
Oh, and I totally agree about the implant!