It seems to me that the problem is one of focus, and branding.

To put it bluntly: who in their right mind would want to read essays by undergrads? Even when I was an undergrad, that's not where my interest was. I wanted to read insightful, thought-provoking, well-researched articles. If those happened to be written by undergrads, well, that was incidental.

So, my suggestion: rename the Journal as "The New England Journal of International Relations" (or some such), and kill the "undergraduate" angle.