How to rebuild App without updating the Discourse and Plugins?

I am stuck somewhere in discourse, because of new Update. I can not run javasripts in the posts after last Update. Now i shifted back to the old Version of discourse (I have backup of it.) Now i need to rebuild the app to meet the RAM and CPU but it will update the discourse again and my website basic functionality will breake again. How can i prevent this ? Rebuild the App without updating the discourse.