The offline files are not saved. The references to the locations on the tapes are saved in the project file. So you can recapture them.
I suggest that you capture a couple of short clips in a new project. Unlink the media, close Premiere Pro, and delete the media off of your hard drive.
Open the project again and mark the offline files to be recaptured.
If you experiment a bit you will gain the confidence necessary to trust the procedure for your real projects.
Steven
Adobe Premiere Pro 1.5 / After Effects 6.5 Pro
http://www.stevengotz.com
Learning Adobe Premiere Pro 1.5
http://www.lynda.com
Contributing Writer, PeachPit Press, Visual QuickPro Guide, Premiere Pro 1.5