Opencart Theme Designing without editing root files

Question

I am working on Open Cart and i am unable to edit theme in open cart so that when i upgrade my open cart version to new open cart, my code remain stable. Even i have used VQmod and VQ manager for it but these give permission to work with cache and when i delete cache my code goes out. I made my own theme folder and make it default theme using admin panel but one problem is that if i will upgrade my open cart version then modification will be done also in my theme which i don't want. Please suggest me some ideas.

Answer 1

Use This code its work.    
<file name="catalog/view/theme/shopitout/template/common/header.tpl" error="abort">
                <operation info="">
                    <search position="Replace" offset="" ><![CDATA[<img src="<?php echo $logo; ?>" title="<?php echo $name; ?>" alt="<?php echo $name; ?>" />]]></search>
                    <add><![CDATA[<img src="image/data/my_logo.png" title="<?php echo $name; ?>" alt="<?php echo $name; ?>" />]]></add>
                </operation>


            </file>