Song is not available (iTunes deletion)

[LuisLansdall]

Since getting Spotify Premium, I decided that I didn't need my iTunes library anymore - it was taking up a large proportion of my memory and I wanted to make the full transition into streaming Since doing this however, every song that was originally on my iTunes will now no longer play on Spotify. When I attempt to do this, it appears with the text 'Song is not available. If you have a file on your computer you can import it.'

How can I fix this so i can stream these tracks like I do with every other track that wasn't previously a file on my computer?