Advice for dealing with a depressed dog

Until three weeks ago, I had two Sharpei/Retriever littermates who were 8 years old. As far as I can tell, the longest they've been apart in their lives was a few hours when Wanda was in the vet.
   
Kazu died suddenly at the beginning of the month and, at first, Wanda seemed like her normal self. She's fairly aloof and independent, not very cuddly or lovey.
   
In the last week, Wanda has been especially withdrawn. I'm sure she's depressed, but I'd like to be able to help her. I don't know what to do.
   
Any suggestions?

Get her a new dog friend. She's missing her littermate & wants company.
   
Take her to an adoption event & let her pick out a new friend for herself. The breed doesn't matter.
   
In the meantime, keep her busy. Take her to dog Meetups (www.meetup.com) and the dog park, & take her on rides in the car whenever you can. Pay lots of attention to her.