Looks like this works exactly like I need it to - Clever! I should even be able to simplify it to timePassed += time_frame*62.5. It does seem to jerk slightly when loading the next level, is this compensated for or will this delay build up as more levels are completed?

Edit: After some playing around, it looks like this delay is compensated for following hard-drive access. This is a great solution - I'll let you know how reliable the timing is after I do some testing!