Import and replace existing page/post content

Is there any way to import a basic, exported WordPress content XML file and have it replace the existing content? What I’m trying to do is synch up two instances of a site (development and staging servers) and all I want to replace is the Page content. When I try to import the XML document it simply states that all the pages already exist and nothing is done. Is it possible to override that warning and replace the content of the pages with the content of the XML?

How to add an export function to a custom Option Theme Page

I’m creating a new WordPress template and I have a question:
I’ve added a custom Option Page to my new template (you can see what I’m doing Here and Here) but now I would like to add a new function.
Do you know Si Contact Form? In this plugin the end user can download a backup of all the settings and Upload it on a different website.
I would like to be able to add the same function into my new option page.
I know how to backup my settings logging to phpMyAdmin but sometimes end-user can’t login to phpMyAdmin or simply it’s better that he/she doesn’t login to phpMyAdmin :-).
Have you got any solution to this?
Actually all my custom functions are named:
‘appaqua__zona1c’;’appaqua__zona1x’ and so on… my theme shortname is appaqua.
Please by kind with me, I’m not a professional programmer and I’m really sorry if I used wrong words to explain what I need.
Thank you very much to all!