Hi Zero,
So if we understand properly, the public IP pool provided to you by ISP is not enough for your network and hence you have requested for few more Ips.
If the ISP is the same and the old public IP provided by ISP is the same, then you do not require to change the public IP.
However if the subnet provided by the ISP for renewd IP is in the same subnet then you need to configure proxy-arp on the SRX so that request for those IPs should reach SRX reth1.0 port. Also you need to configure security policies for the IPs to be allowed to pass the traffic.
nothing else is required to be changed
regards,
Guru Prasad