Repartition hard drive with bootcamp on it
Yes, this is dangerous and uncertain. Just to be safe, and to plan for the worst, expect that all your partitions will be destroyed by the process, and that you may need to reformat your entire hard drive and re-partition it to the new partition scheme that you require, after which you will have to restore your Mac OS X volumes and your Windows Boot Camp partition and restore your Windows installation to that new partition.

You had better make a complete backup of every partition to external hard drives before you do anything. You can use the donation-ware utility Carbon Copy Cloner to clone your existing Mac partitions (Macintosh HD and the hidden Recovery HD) to an external hard drive formatted for Mac OS Extended (Journaled).

You should purchase whatever Windows software is necessary (Symantec Ghost, etc.) to clone your Windows partition while booted into Windows itself. You should clone it to a different external hard drive formatted for Windows NTFS.

Only once you are sure that all your partitions are backed up should you undertake the re-partitioning in Disk Utility. If you are fortunate, everything will go well and you will not need to re-install anything. But since you cannot be sure that this will happen, you would be very wise to have backups of everything first.