Use APKPure App
Get ROM Updater Free old version APK for Android
Gestionnaire de mises à jour OTA pour CyanogenMod 12.1
Do you miss OTA feature from Stock rom?
Don't worry with this app you'll have it on your cm 12.1!
This app is only working on my cm 12.1 builds for janice (i9070), so if you try to use it on other roms, of course it won't do its job.