you have two options depends on your requirements and SRM version. First one is IP Subnet level IP customization which is implemented in SRM 5.8. You can find more information at: VMware vCenter Site Recovery Manager 5.8 Documentation Center. The second one is manually customize IP properties for a VM - here is link with details: Site Recovery Manager 6.1 Documentation Center
Hope that this helps,
By default the IP address (and all other characteristics of the VM: mac addr, name, etc) will be preserved. If you want the IP to be changed, as mentioned previously, SRM can do that for you.