Hi there, Gage, and thanks for the question!
Unfortunately, we don't provide that service just now. You have to download the entire dataset.
Our OAI-PMH feed would be better for you, if you are looking for incremental updates however it doesn't yet include removals (drops). We have a piece of development scheduled for next year to do that. We publish a list of journals removed from DOAJ instead:
When a journal is removed from DOAJ, all articles are withdrawn from the index.
Best wishes
Dom
------------------
Dominic Mitchell
DOAJ Operations Manager