Sevver, great advice. Ken, a couple more points that might help. Raising is always easier than digging down. But if you are planning on reusing the existing liner I would do the side opposite the skimmer opening. That way you do not have to realign the openings. Make it a one day project so the liner does not shrink to much. If you raise the uprights I would definately add some more sand and resmooth before putting the liner back in place.

Best of luck, Dennis