update-rc not work for me, but standart online resize work.
first create backup image then:
sudo cfdisk /dev/mmcblk0
delete partition and re-create (this can be risky, parttition mist start from same sector - in this case 2048), save and then:
sudo resize2fs /dev/mmcblk0p1
if resize2fs can't resize, reboot and run resize2fs again
then you can check disk at next boot:
sudo touch /forcefsck
this is for expanding partition.
for shrinking (this is risky), first resize2fs with lower size, then delete and re-create partition with smaller size, but bigger than size after resize2fs, after that you can clone and expand partition to fill new card...
