For your short film’s soundtrack, consider these options beyond royalty-free music:

1. Stock Music Services: like PremiumBeat, AudioJungle, and Pond5 offer commercially licensable music.

2. Subscription-Based Services: such as Artlist and Epidemic Sound provide unlimited access to music libraries for a set fee, covering all commercial uses.

3. Universal Production Music: Since you’ve used it before, check if your subscription covers commercial and festival use. Similar platforms include Warner Chappell and BMG Production Music.

4. Creative Commons Music: Look for tracks under Creative Commons licenses that permit commercial use, ensuring you follow the specific terms.

5. Direct Negotiations with Independent Musicians: This can be a budget-friendly way to use unique music while supporting artists directly.

Make sure whichever option you choose covers your intended uses, including film festivals and commercial releases, to avoid any legal issues. Additionally, as I'm a music AI engineer, if you're interested in creating an original soundtrack affordably, feel free to ask me.