I need to make this change as well. My client requires the password reset link to be valid for at least 2 weeks.  I can make the code changes if someone could point me in the right direction it might save me several hours.

There are two different password reset expiration periods - one is for resets initiated by the user (i.e. on the login screen) - as Mike says this is configurable in host settings. The second expiration is for when an admin/host reset's a users password - as the user may not be expecting that to happen the period is longer. At present it's hardcoded as 24hrs (I've no problem making it configurable but I don't recall someone logging it in jira yet).

If you want to change the admin reset expiration you'll have to edit   DesktopModules\Admin\Security\Password.ascx.cs - look for the following and change the 1440 to your desired value (it's in minutes)

//create resettoken valid for 24hrs

 UserController.ResetPasswordToken(User,1440);