You can do one of two things, first is after you press the Display button you can then press Regen.
The second is you can have the button do the regen for you, to do that all you need to do is go to Operator menu then Edit Button Scripts.
You will see the Display button flashing, click it and the editor will open, if you place the following after the code and then click File and Save, it should work as you want.
The code to add is
DoOemButton(160)
So the full code in the button should be like below.
value = GetParam("Boundry")
If value = 1 Then
SetButtonText " Job "
SetParam "Boundry" , 0
Else
SetParam "Boundry" , 1
SetButtonText "Machine"
End If
DoOemButton(160)
Hood