There is a way.
you'll need an iPhone as well.
delete WA from iPhone, afterwards install clean, do not open WA.
install UDIDfaker from Cydia on iPhone
in UDIDfaker for WA set the UDID from your iPad
now open WA on iPhone, insert phone number(needs to be second number not your iPhone number, you can use a prepaid or other phone)
WA will now sent a confirmation nr to that phone number.
activate WA with the that nr on iPhone.
Now go into iPhone file structure:
var/mobile/applications/Whatsapp/Library/preferences
copy net.whatsapp.WhatsApp.plist
On the iPad install whatspad from cydia
install Whatsapp
in the same directory on the iPad copy the plist from above.
Whatsapp should now work on the iPad.
On the iPhone remove the whatsapp
install again
make sure UDIDfaker is set to original UDID for iPhone
Open whatsapp on iphone, put in the original number from iPhone and activate again.