Super glue, if it doenst work, buy new trim.
or find a used one in a junk yard for like 40 cents.

 

The clips can be replaced, I just don't know the part numbers.

 

Junkyard could be a good call. Does the trim come in one large piece or a few smaller pieces.

Clips on the trim side? They look to be molded into the trim.
I know on the car side they can be popped in and out, thus replaced.

 

The trim does come all in one piece, but finding one in a junkyard is going to be hard. I waited for like 6 months to find one and had to break down and get it from the dealer.

The clips on the car side go in but once you clip it in it does not come out real easy. The ones on what looks like where they would seperate are molded to the back of it and if you deform one to bad it won't stay well, and the ones forward of that pop into a channel that goes the whole length of the trim.
http://www.realoem.com/bmw/showparts.do?model=EV53&mospid=47725&btnr=51_3267&hg=51&fg=20
Number 14 is the clip that goes in the car end.
Hope that helps.