To me, the continued funding is related to a real and honest attempt to find out what happened to Madeleine. Madeleine’s case may bring to the surface a context that may lead the way to other missing children cases. My view is that the person who took Madeleine, plays a small part in the whole. It might be that the person who took her, is already in custody and that s/he has no knowledge of where she might be.
I agree with that post Anthro; In my opinion it is highly likely that Madeleine's case might have revealed other investigative opportunities widening its scope and which have had to be followed.
Like you I do not think Madeleine's case is being dealt with in isolation.
I think it is incredibly naive of some to think that nothing is happening just because we don't know what is going on.
As long as the police are requesting finance to continue their investigation they must have a valid reason for doing so, as well as being able to justify the request.