This would be hard for me because I don't really leave Ayu, so nothing can bring me back.
I do go through periods of listening to her very often and then periods of not listening to her. I guess when she releases a new album is when I start listening to her very often, but sometimes I'll have a random craving for her music.

But songs that remind me of why Ayu is special to me in the first place are songs like: Fly High, Daybreak, Dolls, Together when, ever free, appears, To Be, Jewel, Rainbow, Who, monochrome, Hanabi, immature, Guilty, fated, teddy bear, A Song For xx, Powder Snow, Heartplace, ourselves, alterna.
I guess all the poignant and heartfelt songs it turns out.