How to reload adf taskflow in Webcenter portal 12c popup window?

in WCP template, adding a link to display a popup window with an adf taskflow. everything works fine. the only issue is when the popup close and reopen, the input fileds in the taskflow do not clear out and still display the previous value. here is my code:

<af:link id="mylink" shortDesc="My popup Window" text=My Popup">

    <af:showPopupBehavior align="startBefore" alignId="userMenuLink" popupId="myPopup"/>

</af:link>

<af:popup id="myPopup" contentDelivery="lazyUncached">

    <af:panelWindow modal="true" clientComponent="true" title="Change Password" contentWidth="500">

       <af:region id="wc_mypopup" value="#{bindings.mypopup.regionModel}" xmlns:af="http://xmlns.oracle.com/adf/faces/rich