Best practice to load new build and run existing tests / parameters / body / variables?

Hi all,
I have a few issues of which I require a little bit of help. I have done some digging around in support but haven’t been able to find answers (apologies - I’m sure info. is there, maybe I’m not looking for the right things).

Our API code is not developed in Postman, and when a new build is created - I have been manually copying/importing the large JSON file into Postman as a new Collection (all endpoints created etc. - and I can run them fine). However, I have tests / pre-req. scripts / variables / bodies etc. created in the existing collection. I have been manually duplicating these from my existing collection and copying into the newly imported and running → is there a better way to do this?

Thanks in advance!