Associate VM floating ip always use old IP

Hi,

We hit one problem during associate VM floating IP to VM.

In our openstack cloud, we did below

1. We have one existing image, name image1 which is based on one rhel 7.1 x86_64 arch
2. We deployed new VM named vm1 from image1. It worked well and got correct IP, we assume ip1
3. Then we did some additional configuration for our vm1
4. Then shutdown vm1, and create snapshot from this vm1.
5. Make this snapshot to public, named snapshot1.

Question 1: Seemed I can not change it to image through Horizon UI, right?
Even this snapshot was changed to public, it is still snapshot, not image, right?

6. Then I try to verify if this snapshot1 work
7. Deploy new VM named vm2 from snapshot1
8. Deploy successfully, vm2 also started, but we hit one problem that this new vm2 still use old ip1.

Question 2: In my opinion, we want to new vm2 to associate new ip, for example , ip2.
Am I right?

Is that mean snapshot can not associate new ip? Only image can do so?

Could you guide and support ?

Thanks!