Here's an idea

I saw this recently, and for the record agree it was pretty lame.

I don't proclaim to have a better idea, but this is something I thought of based on the first few lines of the plot synop:

The kid dies, a doctor offers them a chance to have him back via cloning. The difference is the child is already aged correctly rather than reborn. He explains this is a highly illegal process, they are bound to secrecy, they must sign an NDA, it will cost them a fortune, can be accomplished with something as simple as a hair, yada yada. They agree, and within a week or so they have their child back exactly as they last saw it.

A few months go by without incident until one day the child is getting a haircut, and they notice a tiny scar on the back of the child's head. They try to contact the doc to find out about the scar, but doc appears to be missing. A bit of investigation proves a fruitless endeavor and the family moves on with their lives.

A few years later a news story breaks that Interpol has just captured a man in Germany who looks very much like the missing doctor. The story develops over the weeks, turns out the man is a convicted murderer who now stakes out potential families all over the globe (i.e. rich enough, obsessed with their children, etc), kidnaps the child and 'reproduces' it via cloning for a price. The child is injected with some sort of serum which precludes any memory of the event, yada yada.

The story could simply end with that as the 'shocking finale', or any number of further developments could take place, such as the kid going crazy and killing himself, the father taking revenge, etc.

Again, just an idea that popped up, seemed interesting.