Don't be seduced by the marketing hype!! They're experts in relieving you of your hard earned cash for a few upgrades.
Ok, so the 7DMk2 is a great camera body for sports and wildlife, with its tracking AF system and high ISO range, but does it justify spending £1500!!!
Can't you get a firmware upgrade to increase the ISO range on your current body?
If you want it that bad, then you will convince yourself by whatever means!
Do you want to take night shots hand held with huge ISO? I just use a tripod @ ISO100.
I doubt whether you will see a big difference in shots compared to your old 7D to justify spending £1500, but its your choice in the end.
If it was me, I'd probably wait a couple of years then buy a used body.
Good luck in deciding and lets know what choice you make
Edit: Link to some high ISO shots with the Mk2 http://mattgranger.com/7d2 .......nice!