This MUST be the FIRST action button, because this trick depends upon its position, which must not change.
Open the form from a browser.
View the Document(Page) source in your browser.
You will see something like this where the first button's code is:
Copy it to the clipboard.
Now, for each keywords field that you want to refresh on a click (like selecting a radio button or checkbox), paste it into the HTML Attributes so the syntax looks like this:
For fields that need to cause a refresh on change rather than click, change OnClick to say OnChange.
Now you can hide that Action button, but never remove it.
You can also call
_doClick('$Refresh', this, '_self', '')