Sounds like you are trying to streamline your development.
I am not aware that you can instruct the builder to take care of selected containers only.
Have you taken a look at local mode ( https://www.balena.io/docs/learn/develop/local-mode/ ) ? It might not be what you want as images are created locally and on a RPI that might be even slower than recreating the whole project but in the balena cli docu to push ( https://www.balena.io/docs/reference/cli/#push-applicationordevice ) I found this:
When pushing to a local device a live session will be started. The project source folder is watched for filesystem events, and changes to files and folders are automatically synchronized to the running containers. The synchronisation is only in one direction, from this machine to the device, and changes made on the device itself may be overwritten. This feature requires a device running supervisor version v9.7.0 or greater.