Often the door is a made of an inner and outer shell with a sandwich of filler in between. You may be able to pry the two skins apart and replace the inner material, or at least reinforce the area where the struts attach.
As an alternative, consider mounting a flat metal plate several square inches in size over the inside where the struts have pulled out. Glue and screw the plates on, then mount the struts to the metal plate. The plate spreads the load over a wider area. This technique works if the old strut mount screws have pulled out but the rest of the inner filler is fairly sound.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL