Hi Katrice,
It is depended on the requirements of the application to decide on reloading the whole application or just invalidate the nodes (e.g. must retain some node information, etc.)
If you want to go with reloading the whole application approach, you may want to use EXIT plug, please check out this thread.
How can i get same result as IE's REFRESH action
If you want to go with the clear all screen elements approach and have problem with accessing view attributes from component controller, you can raise an event from component controller and get it handled by the view. Please check out below link:
Events and Event Arguments - Developing Web Dynpro ABAP Applications - SAP Library
Hope it helps. Cheers!