[zone1creative]

I have managed to add a reset filter button.

Do the following

edit the skin1/modules/Advanced_Filter/customer_filter.tpl file

change

<div class="filter_input">
  <input type="button" value="{$lng.lbl_bcse_advf_filter_input}" onclick="javascript: apply_filter();" />
  <input type="button" value="Reset Filter" onclick="javascript: reset_filter();" />
 </div>

to

<div class="filter_input">
  <input type="button" value="{$lng.lbl_bcse_advf_filter_input}" onclick="javascript: apply_filter();" />
 </div>

then edit skin1/modules/Advanced_Filter/customer_filter.js file

add the following function below the apply_filter()

function reset_filter(){
    if(!document.getElementById('customer_filter'))
        return;

    var wrapper = document.getElementById('customer_filter');

    var selectObjs = wrapper.getElementsByTagName('select');

    if(selectObjs.length < 1)
        return;

    var filter_query = '';

    if((!target_content_id || !document.getElementById(target_content_id)) && document.forms['filter_form']){
        document.forms['filter_form'].elements['mode'].value = 'filter_update';

        document.forms['filter_form'].submit();
    }else{
        ajax_filter_refresh(post_action,filter_query);
    }
}