I am just wondering why the application form usually asks"Have you ever applied for our law school？ Why do they want to know this?
If I reapply in 2007, will they put me in a disadvantageous position?????(an abandoned guy!!!!)

i don't think it'd be necessarily disadvantageous...
some people re-apply for many different reasons...and in most cases with extra credentials and/or experience...that should be an advantage...just an opinion...

I think that the "reapplying" status doesn't hurt. If any thing it shows your dedication to attending their school.

I would guess it is also one of the ways in which they make their own life easier - if you have applied in the past, they should have a file set up with your documented profile. So adcom can avoid doing something it has done before.