How do I re-block someone without having to wait 48 hours?

Same way you block someone but after you unblock them you may have to wait 48 hours. Not sure about the waiting part.

On your timeline page click gear icon on top right. Choose Settings. In left side, under "General" click "Blocking". Anyone whom you have blocked should show here and be followed by (in blue letters) "Unblock" - click on this.
I believe FB settings will unblock that person and not allow you to re-block for 48 or 72 hours, so if that may be a problem look into that further. Good luck!

you need to re-activate your account first in order to block the person again.

Hi,
you can't do it.
Go to Settings > Blocking > Unblock the person. Then you can search for him/ her*.
*- Can take up to 48 hours to unblock the person.

ur account will Start after a 48 hours

some times you send many request to many people so facebook is blocked your request so no problem wait and facebook will unblocked your request.

Click Account on the upper right hand of the screen.
Next click Privacy Settings.
Click Edit Your Lists at the bottom center of the screen.
The list should show up toward the top of the screen, just click Unblock next to the name of the person you wish to unblock.

its simple. when you log on, under where it says account on the top right hand corner you will see Account, click it and select account settings, scroll down to where you see Privacy settings click it. once there on the bottom you will see block lists. there you will find what your looking for. just type the name of the person you wish to block

Hello.
If someone has block you, it means that person doesn't want you to see him/her profile or contact him/her in any ways.
So, you cannot unblock it if someone else on facebook block you unless that person unblock by himself.