Hmm actually I think I have even better idea.

1) You clear ALL buy orders.
2) You create BTC2.
3) You move all existing BTC account balances to this BTC2 balance.
4) There's nothing you can do with the BTC2 except put up a withdraw request.
5) All future trading happens on real existing BTC.
6) The new "reinitialized" BTC can be withdrawn without waiting.
7) You collect BTC fees and pay out the "BTC2" withdraws with it.
And there's also another extra possibility :
You can create a BTC2/BTC market where people can try to sell their BTC2 for real BTC, obviously at a lower price, to try to get money that you can actually withdraw without waiting. Some who have some faith left in you paying out the debts in the future could invest and buy BTC2 at for example 1.3 BTC2 for 1 real BTC.

And since your exchange can't handle LTC based markets at the same time with BTC based ones, I think you should close the markets I mentioned above that are no longer suitable for BTC.

Trading with the current imaginary BTC balances MUST STOP. It only creates more people that can't withdraw.