What update is it losing? Can you explain this in further detail?
What version of Lightroom?
What operating system?
I'm using a Mac Book Pro. There seems to be 2 versions of lightroom available on it.
When I log into adobe and am able to use lightroom CC the files are recognised. Using Lightroom 5, (resident on the Mac) the files (Raw files from Canon Eos 7mk 2 (Camera Raw) are not recognised even though I have run 'updates' on several occasions.
Operating system is 10.9.5
What version of LR do you actually have installed on your Mac? Use Help / System Info to find out.
Lightroom version that does't work is Lightroom version: 5.5 
Lightroom version that works is Lightroom version: CC 2015.3 [ 1052427 ]
The Canon EOS Mk2 support was included with LR 5.7, the best choice is use LR CC 2015.3.
However you can update LR 5 to the latest version LR 5.71. and it will also be able to work with the raw files from your camera model.
Hint Adobe has to work on providing support for raw files from new camera models after their release to the market. So if your latest version of Lightroom was issued prior to your camera model it will not have support for the raw files. Hence the need to update.
When upgrading LR and PS, Adobe always does a side-by-side install when installing a new major version (5.x to 6.x).
If you are happy with the way LR 6.3 (2015.3) is running, you can uninstall the old 5.x version since the old and new catalogs are not compatible with the opposite versions of the software.