Can I resize a BootCamp partition without re-installing Windows?
if you intend to lower the dimension of bootcamp partition you can make use of this.
and also if you intend to increase the partition dimension you can make use of CampTune.
if you desire do it free usage this method (Malicious link got rid of - - see remarks) it requires 2 applications (both are free)
p.s : some software program download link in write-up was corrupt you have to download and install these applications from my web links.