I always told her that she plays without her mind. I just couldn't find a way yet to motivate her :-(
Are you listening to the CD fifty times per day? I recently went to the Every Child Can Suzuki Introduction Course. They said you have to listen to the CD up to fifty times each day with your child in order for it to properly sink in. Personally, I never had trouble memorizing the Suzuki pieces as a small child. I learned all of the pieces in book 1 and graduated after three months of Suzuki lessons into book 2 when I was 5. It was because my family ate, slept, and breathed Suzuki every single day. My brothers and I all had Suzuki lessons on two different instruments. I would recommend starting a string instrument. Suzuki method was developed for strings first and foremost. Don't put all of this pressure on the poor kid! She shouldn't be worried about memorizing things correctly/incorrectly at this stage! Just listen to the CD fifty or so times every day. Suzuki is all about monkey-see-monkey-do.
Then we dropped because I felt she wasn't motivated enough to play but I still don't want to give up piano on her. So I still help her practice at home for 30mins a day and just hoping one day she might be interested and can easily pick it up with teacher.
As said previously, she needs to enjoy and breath music!If you want her to be more "active" mentally doing music, I don't think suzuki is the method to be honest. Combine it with more imagination driven playing at the piano. For instance, put the pedal down (of let her do it if she reaches) and let her play and explore the black keys. It all will sound lovely in the pentatonic. Let her do big noise, and very quiet one, in the whole register of the piano!Also, story telling at the keyboard. you can have bells, and play tinkling sounds at the top. Or a thunder storm, and just rumble at the bass. Don't censor her, let her love the instrument and connect to her imagination with it. Sing lots with her too. There is very good books that have very very easy arrangements of nursery rhymes. Always more motivating when they like the music and they know it before hand, so she can asses her improvement. Sing and play together. Don't forget the "play" part of playing the piano...
If you really want your child to develop mentally through music, enroll her in a youth choir that rehearses once or twice a week. Get her lessons on a second instrument, preferably a string instrument such as cello. She needs to be stimulated through music. She needs the involvement of peers for this stimulation to occur. Let her continue on the piano whenever she wants. Seven years old is pretty young for piano-the hands are still so small. Great age to start playing a fiddle of some kind!
If your child don't like brushing the teeth, would you give up on that and let her go to bed without doing it? I know "forcing" is not a best way but sometimes you just have no choices. Just like doing school homework, if kids don't like doing it, you still have to force them to do, right? If they do not naturally like doing something, maybe they can learn to love it when they are good at it.