Carl,
If it is the upholstery that is coming unglued, it can be almost impossible to re-glue it without first getting the old glue removed. Otherwise the new glue just adheres to the old, which continues to deteriorate. Might check with a good auto/RV upholstery shop. Anther thought would be to install some decorative wood strips to hold the ceiling material up, but I fear once the glue starts letting loose, it may spread to the rest of the ceiling. Maybe there is an upholstery expert reading that can give you a better direction.
Steve