Hi @WesPenre 
If I remember rightly, you have a two-container set-up so you won’t have an app.yml, as neither of your containers are called app.
Have you done a rebuild of your Discourse recently? I think letsencrypt should use that as an opportunity to renew your certificates.
If you’re on a two-container set-up I think you can do this by using the ‘access console’ on your Digital Ocean droplet page for an easy way to SSH into your server, and then:
cd /var/discourse
git pull
./launcher bootstrap web_only && ./launcher destroy web_only && ./launcher start web_only