Upsampling and need to keep internal wave file markers

[ggoode.sa]

Hi Guys,
I have a sample set of organ pipe sounds that are 16-bit 44.1khz and I need to upsample them to 16-bit 48khz. Simple upsampling with sox or libsamplerate doesn't work as a new file is created with the new rate and the loop and release markers are not copied across. Does anyone know of a linux audio app that could be used to do this? Preferably with a 'batch conversion' mode? A command line tool would be great too...
Thanks,
GrahamG
Johannesburg, South Africa