I had the same thing happen to a robust porter. I've been sitting on it since September trying to decide what to do with it. I've decided to let it ride in the secondary for 3 more months, then make three new batches to mix in with it. When the time comes I'll brew a dunkelweizen, a Munich dunkel and a Scottish 80/. I plan on mixing 3/4 of each dunkel with 1/4 soured beer and end up with two different mixes plus 1/4 batch of the dunkels. I'll mix half of it with the Scottish 80/ and have 1/2 the Scottish and another mix. I wish it was all done so I could tell you this is a good idea but I'll just have to wait and see!