So why did Kiki begin to lose her powers again?
She lost her powers because she lost confidence in herself and became depressed and aimless. Once she got back on track, her powers returned.
If it were really an allegory for puberty, she would have lost her powers permanently.
She lost her motivation because of a list of social issues. Once she 'grew' out of it, her ability to fly started to come back. The ending purposefully leaves it up in the air if she ever gained her ability to speak to Jiji again, as a symbol of her not having her full powers back. And the idea of lost innocence.
>If it were really an allegory for puberty, she would have lost her powers permanently.
Funny becase Sakura is literally an allegory for puberty and she got her powers back.