So you have multiple runtime/staging environments and need to update the database-schemas in order to make them compliant with your latest entity classes.
This was possible up to now via environments from you local Designer. I think today you could still do it, e.g. by setting environment options right in your Designer app.yaml. The app.yaml also exists at Design time, but it has yet no front-end in the Designer. Nevertheless, you can find it by opening an "OverrideEditor" and hitting the Text-button on the right upper corner of that editor. Then the app.yaml for the running Designer app will be opened. Now you could overwrite value in here by setting your stating values in here and running the update. ... still lot of manual work though but sort of reproducible.
However, many customers don't even have the possibility to access all runtime databases out of their Design-time. This basically gives us a pointer, that schema updates should be done during deployments on the Engine, and not by a detached manual Designer interaction.
Therefore, I'd rather delegate schema updates directly to hibernate whenever required. You can do it by setting the property
hibernate.hbm2ddl.auto=update within your persistence unit editor.
For the future it would indeed be better if you have fine granular control onto the database-schema changes right on the Engine. E.g. by offering an "update" action in the Engine-Cockpit. Or by making manual update-challenges possible at deploy-time. But yet we are not here. Feel free to give us feedback on that topic. So that we get a feeling what is most important to be done on the Engine side regarding hibernate schema changes.