f:event preRenderView with f:ajax

[umajeric]

This post is little off-topic, but anyway:
I have a metadata defined on page:

<f:metadata>
    <f:event type="preRenderView" listener="#{controller.refresh}"/>
</f:metadata>

a button:

<h:commandLink id="btn1" action="#{item.setValue(null)}" value="delete" >
    <f:ajax render="@form"/>
</h:commandLink>

and a primefaces button:

<p:commandLink id="btn2" action="#{item.setValue(null)}" value="delete" update="@form"/>

my problem is when I press btn1 my method (controller.refresh) get called everytime (not only first time I get to the page), but when I press btn2 the same method is called only the first time. Where is the difference?

I wan't to have btn1 without calling this method every time.

thanks, Uros