I used to work in LPCXpresso with LPCOpen for LPC824. There I had a file crp.c where I could set the CRP_WORD to a desired value. Also there were the iap.c and iap.h files from where I called the function Chip_IAP_ReinvokeISP().
I am working now in MCUXpresso with SDK for LPC845, but I could not find some similar facilities to allow me to set the CRP word and to call ReinvokeISP().
Any help would be much appreciated!