If you have changed only IP address of epo, the clients will automatically get updated information throught he next ASCI.
Since, it will try with 3 possibilities as below.
The computers with an existing agent installed will attempt to connect back to the ePO server using the following order:
DNS / FQFN
For more information, check the Kb51529, this article is for different issues, but you will come to know the sequence of the agent communication with 3 ways...
Each and every type will try with 6 attempts, as per your environment, it will try with ip address for 6 attempts, then will check with DNS and then downloads the updated sitelist.xml from epo to client machine to get updated info about the IP address on EPO is changed.
From the epo server, you can find Ip is changed in server.ini file located in <EPO installed folder>\db\ "server.ini " file
I hope this answers your questions,