Sure! It depends on what you are reeferencing though. If you are talking about your IP addy at work and they use static IP addressing then you may not be able to do it yourself.
If you have dynamic IP addressing or are talking about your home broadband connection and you are running some version of Windoze then:
Click the "Start" menu button on the Windows taskbar.
Click "Run" on the menu.
Type 'ipconfig /renew' (leave the quotation marks out!) to get a new IP address.
Poof! Yer done!