I have no more left, how do I upgrade the space? I have a 4 gb sd card. Also I have dkcr3d which takes up 17,000 blocks. If I delete can I redownload it at another time?
You can redownload the games, don't worry.
I also got a 16GB SD Card for my 3DS too, and it's more than enough for me, I suggest getting one. I had the problem of not having much room left either originally when I got DKCR3D aswell. xD