I left Thailand on an ED visa this week. I did not get a re-entry permit. I'll be coming back to Thailand next week on a DTV and will be returning to the same residence. 
Do I need to go to immigration and get a new TM30 on arrival? If so, how long do I have to take care of that? Thanks for your help.
TLDR : Answer Summary
After leaving Thailand on an ED visa without a re-entry permit, you are required to obtain a new TM30 upon your return on a DTV visa. This must be done within 24 hours of your arrival. Many commenters affirmed this requirement, stating that the process is quick and can affect your 90-day reporting, so it is essential to handle it promptly.
90 DAY REPORTING RESOURCES / SERVICES
- Use the trusted Thailand 90 Day Reporting Service to get your in-person report done and mailed to you for as low as 375 THB (even if the online system doesn't work for you).
 - For immediate assistance, contact Thai Visa Centre directly via LINE at @ThaiVisaCentre or Email them.
 - Join the Thai Visa Advice Facebook Group to ask your questions, and get advice from others.