Then just back your card up to your pc--I like to use a sd card reader--much faster
Get new card--sometimes there is software on it you may want to remove--I reformat new ones with sdformatter from web--follow settings recommendations from pdf guide: Format Type--Full Erase ON and Format Size Adjustment On
Then copy bu over to new card and put back in phone
If you are going to continue to flash, think about partitioning--frees up more space on phone--especially if flashing sense roms