We have a large AWS Environment and I want to try if we can refresh the UF to get the apps mentioned for it the DS Serverclass without a restart. If so, how is it possible? Is restart the only way to deploy new apps and start collecting the data?
You do not push from DS. You update your app and do a reload deploy-server. That makes the update available to the UFs next time they check in and they pull the app if the checksum does not match indicating they need the new app. If you are involving changes to inputs.conf then in a lot of cases you do need to allow restart splunkd in the serverclass.conf stanza. Usually such auto restart is not an issue.