John,
I can tell you from experience that restarting SQL Server will not help you with this problem. Your environment variables are getting overwritten by another setting. Probably within the package itself. It's an order of processing problem.
I wish I could remember the details. You might be able to google the issue though.
In my workplace, we often have to change connection settings for our packages. When environment variables didn't work, we went to XML config files. We have one for each of our environments and call the packages using those files. We haven't had a problem since.