Retaining High ranking
 

I currently track a web based site that has no web blogs, RSS or any AJAX. It is a completely still site that I bring up-to-date two times in a month. I physically fix all the HTML coding. In recent times, it got enhanced for a great ranking for more than a few key words. It placed first of 1lac, and 25 of 27lac by Google SE. At the present, I am thinking of modernizing my web based site through this thing called CMS (Joomla). I would need to change the site map, construction and triangulation. On the other hand, I am nervous if I restructure it, then the standing will fall. What do you reflect? Will refurbishing move my present high position in Google? What must I ensure to uphold it?