According to information from ANN:
Wataru Yoshizumi will launch a sequel to her popular Marmalade Boy shōjo manga in the May issue of Shueisha's Cocohana magazine on March 28. Marmalade Boy little is set 13 years after the last installment of the original series. The sequel follows the little sister and brother of Miki and Yū, the main leads of the original series. Miki, Yū, and other characters from the original series will appear in the sequel.
So if you are a fan of the series, and you want more, this is your chance.