Note: This procedure requires editing a game file; creating a backup copy of the file before proceeding is recommended. With a text editor, edit the .xml file in the "save" folder in the game directory. The first line of code should be similar to:
[Game timer="476895"/][State pos="68.000000"/]
When your timer runs out, edit the file and change the value of "State pos" to a higher value such as "500.000000". Note: The other number is your total time playing that level. It can also be changed.