I agree, once its started it will continue to fall down no matter how many areas you reglue. The problem is the layer of backing foam on the fabric - this foam perishes and turns into a powder.
Allow yourself a day for the mod. Get some fabric that suits (I used vinyl as it was all I could get here but it looks good). Remove the head liner and rip off the remaining fabric. Scrub off all the remaining foam from the fibreglass/insulation, glue the new fabric on and replace the liner.
Sounds easy but getting the liner back in place was a major for 1 person, a 2nd pair of hands will be a life saver. Instead of spray on adhesive for glue I used carpet glue and let it dry for a night before putting into the jeep. This was great for vinyl but may soak through normal fabric.
A link to the process is here:
http://www.wlsheadliners.com/tutorials/cherokee/