Well just keep trying.
She is old enough.
There is also a good book called "Have A New Kid By Friday" by Leman, which has some real good tips. It is easy to read.
The thing is, she is ALSO old enough to learn: that she is a PART of a FAMILY... and in order to be a PART of a FAMILY... she has to take part in it. It is not an 'option.'
I tell my kids that and teach them that.
My son, who in only just recently turned 4, will even tell me if I did not put something away "Mommy, you didn't put away the newspaper... we're family... we all help..."
Your daughter, and I have a 7 year old too... can learn.
You just teach them. Don't use rewards or treats... some things, household responsibility, just is. I tell my kids, getting a reward for everything is not the point. It is being responsible. And we are ALL a part of the family... and they can choose to be a part of that or not.
If not, then they can't expect "me" to be their 'slave' either. Because I am not.
Also though, my kids are kids. So, I don't expect them to be like me in terms of how 'perfectly' they do a chore or something. I just tell them to 'try your best..." and that is fine. One time my daughter told me she didn't want to do a chore... because she was afraid she didn't know how or not do it perfectly enough... and then Daddy would scold her or make her do it all over again. So... there is that side to it too.
Next, she is 7 and in 2nd grade... how the heck is she managing that? How is she IN school? Does she even get her homework done? Is that another issue too?
all the best,
Susan