Update/Save widget from page

Hello,

Is there some way to update/save widget from page – not from admin ?

I create widget with charts and do not know how to update it from sidebar. I found of course form in admin:

<form action="" method="post">

<input type="submit" name="savewidget" id="widget-chart_widget-2-savewidget" class="button button-primary widget-control-save right" value="Save">

But what is this ID = widget-chart_widget-2-savewidget … how this ID is created?