Lake Arrowhead? Nice area. We are in Santa Ana and a relative used to let us use their place up there on occasion.
Raising the ceiling is a major task no matter how you do it. Extending the inside walls - if drywall - is easy enough, but you can't just add two feet of studs on top. Then there is the siding to consider.
You need a structural engineer to look at it. There are a couple ways it could have been framed and that would determine how you can proceed.