My HFA son has been going through a phase of swearing when he is having a meltdown or getting really angry. Some of the stuff that comes out of his mouth is insane. I don't do anything about it "in the moment" because he is pretty much unreachable in that state, but later, when we are having a nice moment, like at bedtime when I read him stories and he is all snuggly, I talk about it. I say how it makes me feel, how I don't like being spoken to like that, etc. He is always very apologetic. Then we talk about ways we can deal with the problem. Most of the solutions are about healthy and respectful ways to deal with anger and frustration. The message is to work on getting those feelings out, but in a healthy and respectful way. It's not an overnight solution, but the long-term lessons are priceless as I'm not just correcting behaviour, I'm giving him skills that he can use throughout his life. And I'm also making sure that our relationship stays tight. Because of that he doesn't want to disrespect me or hurt my feelings, and he is motivated to make changes and improve.
I'm not clear on the circumstances surrounding her behaviour, but it sounds from your post that it is an overall attitude towards you and her family. Some part of your relationship with her may be damaged, at least from her perspective, and punishment is only going to make that worse (I get that you didn't mean it as punishment; but that is exactly how she will view it). It may stop the behaviour, but the cost is a disconnect from you, and the feelings that lead to that behaviour will just come out in other, perhaps more destructive, ways.
I think first it is important to understand where the disrespect is coming from. A 7 year old is not really disrespecting you, she is manifesting/expressing some pretty strong emotions in the only way she knows how. So I would encourage you to try to figure out where all that is coming from. Anxiety underlies a lot of "bad behaviour", at least IME, and that would be my first guess. An inability to cope with anger/frustration would be my second.
I would encourage you to find a nice, close moment with your daughter, like bedtime snuggles, or maybe take her out for ice cream, just the two of you. And talk to her. Ask her what is going on (she may not be able to tell you, she may be too young to self-examine like that). Tell her how it makes you feel, do not be judgemental, just matter-of-fact. See what her reaction is. When you know what you are dealing with, you can explain it to her so you teach her to look inside herself to see what is going on with herself. Give her words and language to use around it. Ask her to join you in finding solutions to the problem, or make suggestions based on what is underlying it.