import bpy

def refreshNow(val):
    mat = bpy.data.materials['Skin_Gloss']
    nodes = mat.node_tree.nodes
    nodes["Mix"].inputs[0].default_value = nodes["Mix"].inputs[0].default_value
    return val

refreshNow(0)

bpy.app.driver_namespace['refresh'] = refreshNow

def my_handler():
    refreshNow(0)

def register():
    bpy.app.handlers.frame_change_post.append(my_handler)