You can really make this change to the yolk piece only, if you wish. So first you need to find the difference between where the skirt currently sits on your body to where you want it to be. Make a copy of the yolk pattern piece. There should be one straight side to your pattern, usually the center front that’s placed on a fold. On this line, you’re going to extend the line up to that measurement you took. Take your measurement of your waistline or where you want the top of the skirt to be. I would just do front waist, from side to side, and then divide that number in half, maybe add 1/4″ to this for ease, especially if your skirt is made using a woven fabric. Then use this measurement to create the new waistline at the top of your extended line. Usually the waistline is slightly curved so you can use the top of the existing pattern to help you draw the shape of the top of the waistline. Then connect the edge of the waistline with the hipline. Usually you want to use a hip curve ruler as the line to the hip and waistline are usually slightly curved to copy our body shape. Repeat the process for the back yoke. Make sure to make a muslin with your new pattern pieces to test the fit. Hope this helps.