Instructions
Open the date and time settings by clicking once in the bottom-right corner of the screen on a Windows PC and selecting "Change date or time settings..." You can also go to Control Panel, then "Clock, Region and Language" and click on "Date and Time" in Windows 7.
Click "Change date and time" in the pop-up window. Change the date to the following day by clicking on the number for that day. Press "OK" in each window to save the date.
Refresh the browser you are using to play "RC Laser Warrior" by pressing the F5 key or clicking the refresh icon on the browser's toolbar. The next day's car and track will unlock.