Sounds like you need someone to take in you apron edges and perhaps a pleat or two (assuming the pleats closest to the apron and under apron are not cut out.)

This would cost a small fortune as it's alot of work. (taking out the waistband, lining canvas etc... putting it all back together.)

Depending on your kilts and how precious they may be, it might be a good time to get a new kilt and sell off an old one.