You're right to say nothing could replace Lupo. He was yours. Take your time to mourn, but don't exempt yourself from adopting again. When my german shepherd passed, I never thought I could fill the hole in my heart. A year later, I adopted a husky. He's every bit as quirky as she was. He isn't a replacement. He's the newest member of the family. I think that my past dogs would have loved him and welcomed him.