Imported tables lose security permissions

[srast]

Hello all;
I have a db with secrity permissions for multi user access. The db sits on a server, and periodically I want to back it up and store it in another location. I first delete all the old tables, and then import all the tables with the data. The one issue is that all security permissions for those tables are lost, and I have to redo them for every user. Is there a way around this?
Thanks.
Steve