Have you gone through 16 villagers since he moved out? If you haven't, the only way you can move him back in is if you have his amiibo card. otherwise he won't move back into your town until you've cycled through 16 villagers.
Hi I can scan him in for 15 tbt!
That would be great! Tell me when you're available.
I can scan him in now, it'll take about ten minutes
Is it okay with you if we do it tomorrow? I have to write an essay tonight.