Hello. The live image is built to give you an opportunity to try out Clear Linux* OS before installing. Unfortunately, we have to balance the size of the image and the required resources. We currently do not support installing new software into the live image or upgrading to a new release due to such constraints. The reserve that is there was mainly to support Firefox which gets installed into the home directory of the live user.
We always suggest using the latest published ISO from the download site to have the latest release.
If you are not ready to install Clear Linux* OS onto your permanent media, we suggest installing onto a second USB drive. This will not only allow your settings to persist (the ISO is effectively read-only), it will allow you additional space for software installations on the secondary USB drive.