add options to select in ather page

Hi, I've listbox with some categories in a page. When I find that there isn't the category I want, clicking on a link, I enter in the category managment page. After adding new categories, whenI close that window, I'd like to dinamically reload the select on the opener page, without reload all the page. This because there are other field before the category list. If the user has already filled other field and I reload, he have to refill that field again. Thanks, Carlo