Try Vmware > Proxy Deployment manager from Avamar 7.2 console where you need to feed necessary network and hostname information for multiple proxies you wish to deploy across esx hosts of datacenter.
Once you have all the information loaded, just click on "Apply" on Vmware proxy deployment manager console and it will start deploying all the proxies you had feed information for.
Ensure necessary ports are enabled between Avamar server and Proxies to be deployed.
It basically outcomes the same thing. You can delete existing proxies and perform this deployment at newer version of proxies. This process infacts is more better reliable and smooth and fastest process. I doubt, if there is still any code level upgraded available for proxies by installing just executable files.
Sorry for coming late on this.
With latest Avamar version 7.4, in proxy deployment manager you have an option to upgrade proxies on fly.
Just hover any old version proxy and it should pop as "Update Pending", just click Apply and it proceed for upgrade.