in general it helps to be clear on what node you are using - in particular which node module it comes from. There are 1800+ modules in the community, so it helps to narrow it down.
In this case, I recognise this as the IBM Watson IoT Platform node.
That node doesn't support directly referencing context in its configuration. As it is an Input node, there is no way to pass it a message to set the deviceId dynamically either. So your options are limited here.
Are you only able to identify the deviceId you want to receive events for at runtime? Do you know if before Node-RED starts? If so, you could use an environment variable to insert the value. Otherwise, I'm not sure there's much you can do here.