To see your current IP address from terminal you can use ifconfig command, it will list all of your configured interfaces. If you are using a wired connection the interface will probably be en0 or eth0 (i can't remember which). For more information just type "man ifconfig" in terminal.
Also - even if you request a new lease, you may still end up with the same IP address. Its up to the DHCP provider to issue you one and unless you set yours manually, you have no control.