You probably never noticed, but there is a little black switch on the right side of the NDS. Gently slide it towards the back of the NDS (in the direction of slot-1). It will immediately spring forward after you release it. The NDS will then shut down! Then, slide the same switch again in the same direction. This time, the NDS will turn back ON! You will then be able to get back to the Acekard menu.
It's a little tricky the first time you do it, but with practice it will work each and every time.
As an added bonus, the use of this switch after each game will conserve your battery, keeping you from having to recharge your NDS every 6 or 7 hours.
Good luck!
-Bri
PS: Seriously, the Acekard 2 can't soft reset from homebrew like emulators. It can soft reset from games by first turning on the "soft reset" option (start -> patches -> soft-reset -> enabled). Then, you can press A, B, L, R, and down all at the same time during a game to reset back to the Acekard menu.