adb update a non-market apk?

adb install -r is the closest you get, that is actually an update as it keeps the database and stored preferences. If you uninstall/re-install both the app database and preferences is deleted. What exactly are you trying to update about the app that -r option does not help you with ?

adb install -r didn't work for me. So, I did a little workaround.

1. Uninstall app but keep the data by using adb uninstall -k com.packagename. This will uninstall the app but keeps the data. See this

2. Install the app again using adb install package.here.

Note: You must have root access to execute this commands.

To reinstall a downgraded version of app, use this command:

adb install -r -d package.apk