re releasing an album

[Fabtones]

I'm re releasing an album. Do I have to get new ISRC and ISWC codes?

[Joan]

Hi there @Fabtones,

Thanks for reaching out. 

We here in the Community are more focused on helping with account and app related issues, as well as user feedback. For any questions regarding music you have uploaded or want to upload to Spotify, it’s best to contact our Artist Support team, they can assist you further.

Hope this clears things up.

[UDM]

I think it’s automatically reassigned to the same tracks, as long as there’s not significant changes to the structure or the size of the reuploaded songs. If the changes are significant enough, then you can most probably let your distributor know and ask their assistance for the existing codes. 
For an absolute certainty, maybe ts best you check again with the FAQs but I think it’s more about what your distribution service should be concerned about. I don’t think Spotify is assigning the codes. 
Good luck 😉