Question about method books

[op3no2]

Hello,
I've been taking non-major piano classes at school to improve on my piano playing and we used "Hal Leonard Student Piano Library Adult Piano Method - Book 1/CD" and are using the second one this year for the second part. I'm only allowed to take these 2 classes since I'm not a music major but I want to continue to improve. I've usually just played what I wanted but I kinda want to continue improving as I am now. I was wondering what would be a good book to use after the Level 2 book when I'm done with this class?
Thanks