Since the BNA content is actually stored in the world state, submitting a business network update can be done from any client that has access to the administrative certificates.
Thus, to update the network, you submit the following command:
composer network install -a ./network.bna -c <card-name>
composer network upgrade -n trade-finance-logistics -v 0.0.1 -c <card-name>
In order to test the deployment of an updated BNA, please refer to: https://github.com/HyperledgerHandsOn/trade-finance-logistics/tree/master/composer.
Note that the other dependent components, such as the REST gateway and the application, would also need to be considered in a production deployment.