Moving content to WordPress.com

Hello,
I want to maintain a copy of what I do (at ww.wp.xz.cn) in my previous blog at WordPress.com. Which is the best method..moving the content thru Export option or copying each post/tags/formats etc?

I want to maintain my ww.wp.xz.cn posts as it is while wishing to maintain a copy of all the content at WordPress.com. I want to maintain both(ww.wp.xz.cn and wordpress.com).

I afraid if I move my content thru Export option everything get vanished from ww.wp.xz.cn with out any copy at the same.

What are my options?
Thank you.
RK