I did a partition resize on my SD using GParted bootable image.
1. Write the lichee pi image to sdcard
2. Download GParted image
3. Configure VirtualBox to 'see' the sdcard
4. Boot GParted into VirtualBox, resize sdcard partition from there (make sure to resize the extfs partition and not FAT).
This has very little risk as by the time I'm doing it, the partition only contains the 'fresh' Lichee Pi linux image, so there is nothing to lose if the process fails (and it doesn't fail).