Ubercart

Hi,
I use you wonderfull ubercart on my site, it works very well.
I need to get the site offline for doing update (core, module...).
But I don't want to loose sell !!!
So I need to know if I can reimport all sells information (order.. ) in the new database updated, and what are the tables to copy?
what are thing, that i will forget to do??
I need you feedback, i'm sure i'm not the first to do that....
Regards,