I had to do this too, for updated and a local build.
I used the APSync build from New APSync Build for Raspberry Pi which is based in Raspbian rather than Ubuntu but they both use network manager so this should work.
You’ll need to at the console of the PI since you’re disconnecting the network so can’t have an open SSH connection.
You need to use the network manager CLI tool to get the name of your current access point connetion, disconnect it to free up the Wifi adaptor and then connect to your local Wifi.
nmcli connection show
nmcli con down WifiAP (or whatever your connection is called)
nmcli device wifi connect <your SSID> password <your Wifi password>
Once connection nmcli will tell you your IP address so you can shell in from elsewhere if you need to.