You can release renew the IP addresses on the windows machines by running a command in command prompt. That being said may I ask why? Your computer will automatically re-lease the IP address after a set period of time automatically and really isn't needed.
Equally the phones will be more difficult to do. To refresh all IP addresses you can disable and then re enable the DHCP service on the router and restart the router. That being said, some devices will just use their original addresses to avoid conflict.
Command line is as follows:
Hope this helps,