i have some suggestions. Trying them depends on how much you love your jeans! First, try using a boil wash- which may shrink them. However, i have done this with little ill effect. Secondly, soak them in a mild bleach solution. This, however, can weaken the material. You then need to wash them a couple of times, to remove all traces of bleach. Alternatively, and this is probably the safest way, though will take a long time, every time you do a wash of similar colour/material put your jeans in whether they need it or not. I believe there are, or used to be proprietary products that 'naturally' fade jeans.
There is a site here
http://www.sptimes.com/2003/10/13/Xpress/Makin g_the_fade.shtml that has some information that may help.