You can renew your IP address simply by restarting your computer. To force a renew without restarting, simply follow the steps below for your operating system.
Open the start menu, click run, and type 'cmd' to open a command windows. Now, enter the command 'ipconfig -release' and then 'ipconfiig -renew' to renew your IP address.
Open the start menu and type 'cmd' in the search box. When the results appear, right click on 'cmd' and choose 'Run as Administrator'. Now, enter the command 'ipconfig -release' and then 'ipconfiig -renew' to renew your IP address.
Open a terminal window and type 'network service restart'. This will restart the network service and effectively renew your IP address.
Open the 'apple' menu, select 'System Preferences', and then 'Network'. Now, select 'Ethernet', click 'advanced' (or 'configure', in older versions), and then click 'Renew DHCP lease'.