The LR 5 stand alone (perpetual version) with a full license key (or previous version + upgrade) is the same software as the Lightroom 5 CC, just a different procedure for activating the license.
Just use the normal procedure for your operating system to uninstall the existing LR 5 CC, this process will just remove the software application and will not interfere with your Catalog File, Preferences and personal files. Then download the latest version of LR 5 which is presently LR 5.6 then run the install package. It should connect with your existing Catalog a everything will be fine. If LR 5 was previously installeg on your existing system it may even reconnect with your original license key. In any event before proceeding ensure you have the License Key available including an earlier version if your LR 5 Key is an upgrade.