If these tables are only being used for transactions (best way) then put the connection string in a module and and make a call to it every time you want to do a transaction, then all you have to do is change the string in the module - assuming the table names are the same and the table owner is the same.
If these are linked tables, you may have to delete the tables and re-establish the links. There have been some recent posts about managig linked tables. I generally don't use linked tables.
Look it up at: http://wrox.books24x7.com