There is no inherent function of a form that refreshes it, unless you're talking about redrawing it on-screen, which you're not. If you want the form to get new data and display it then you have to write code in the form to get the data and display it. There's nothing magic about it. However you displayed the data in the first place is the very same way you you display new data a second time.
If you want to initiate that in the form then you do it exactly the same way you always initiate something in an object, i.e. you handle an event of another object or another object calls a method. Does your other object have a reference to this form? If so then you can use the second option, otherwise you would use the first option.
If you're still confused, maybe you should show us some relevant code, mainly how each of these inter-related objects is created and uses the others.