If you are using an emummc then you need to use some tool like CheckPoint to export all your saves from the old sd card.
They are just files on the SD card after they are exported.
With a PC you can copy them over to the new SD card and with CheckPoint you can import the save files into your new emummc.
FYI : the save files are normally stored on the sysnand but the emummc is a copy of the sysnand and thus all your save files are located in the emummc partition on your sd card.