You need Automation Studio, which you can get a 30 day trial of from br-automation.com. B&R compiles the project and stores the binary files on the CF card, while there is the option of storing the source code also, it is not the default option and so it is unlikely to be on your PLC.
You can still upload the binary files using Automation Studio and/or create an image of the CF card for backup, but without the source project, you won't be able to change any logic (so you won't be able to change where IO is mapped to avoid damaged IO points). If you replace the IO with the same model, the PLC will take care of firmware and configuration, so you won't need to do anything with the project.
If you are very lucky, the source project will be stored on the F:\ (user partition) of the CF card and can be downloaded by FTP into the PLC. You must enter a username and password (typically br:br, but anything should work) to unlock access to the F:\ partition and use an FTP client capable of changing partitions (CoreFTP Lite is what I like to use). Otherwise, contact your OEM to ask for it. You should find it as some kind of zip file or maybe even as an uncompressed directory.
Newer versions of Automation Studio can automatically store the source project on the CF card in a special file. You upload that using Automation Studio's "Open Project from Target" option once you are online. The 2005 series is pretty old (came out in 2000), so your machine probably pre-dates this feature.
