Have to re-download repeatedly

[Lukas176]

Four times now my entire catalog has undownloaded itself and I have to redownload. I don't have wifi access. Getting very old. Anyone else have this problem

[Zuzakon]

So this seems to be happening to some people. This is an issue that Spotify has to fix, however from what I have seen people have found some fixes to it that you may try.

1) Solution from anjieeeeeeeeee 

"First thing you'll need to check is your internet connection. You've got to make sure everything's synced before you disconnect from wifi.

If internet's a-ok and everything's completely synced, maybe you'll need to refresh your device that has offline songs.

Go to your Account Overview then remove your offline devices here -- https://www.spotify.com/account/offline-devices/
Then you'll need to reinstall the app.

This means you'll need to re-sync everything, but this usually eliminates any cache problems (cache is where offline songs are stored)."

2) You can try getting in touch directly with Spotify, because the problem can be directly connected to your account. Also it is good to make them more aware that this is a reaccuring issue for many users. 
You can do that by Spotify support form or by Twitter

Hope that helps