Dissasemble the laptop. Locate the broken insert for the metal bushing which holds the hinge and remove it. Drill a small hole in the center of the cracked plastic insert.
Step 1: Metal Bushings
This is the metal bushing which is placed into insert on the plastic case of the laptop. It is almost impossible to glue it, because some laptop manufacturers use special plastic for the laptop case, a plastic which does not stick with most glues, also there are a lot of tension in the place where the insert is located and after several times you close and open the laptop lid, the hinge base will crack again. Notice that this little thingy have thread from end to end.
Step 2: Drill Holes and Refit Bushings
Put the metal bushing back to its place and screw it with a small nut from the bottom side of the laptop. I recommend using appropriate washer because if the nut have small head it might go right trough the hole.