Unfortunately, I do not know of an at-home way to
do this.  I once had some dougas that were stuck
to their cels removed by SR Labs. While they were
at it they removed the stuck cel layers too.  They
did a nice job.  It's just that it can be a little
expensive.  They also have a long back log.  The
last I heard, it was about 1-year wait.  It's a
good option for a more expensive or much-loved
cel, but for the ones you don't want to spend the
time and money on, you're probably out of luck.  
...Sorry...