View file templates/admin_subscribers_filter.tpl

<form method="POST">
<input type="text" name="s_text" size="20" value="{$s_text}">
&nbsp;&nbsp;<input type="submit" value="Find"> 
<input type="button" name="Reset filter" value="Reset filter" onClick="document.location.href='./index.php?r_filter';"></td>
</form>