Place chicken on plate; brush both sides with lime juice. Sprinkle chili powder and cumin over both sides of chicken; let stand 10 minutes.
Preheat grill or broiler. Grill or broil chicken 5 minutes per side or until cooked through. Cool; cut into 1/2-inch pieces.
Heat broth to a boil in large saucepan. Add tortilla chips; cover and let stand 10 minutes. Puree mixture in batches in food processor or blender; return to saucepan. Stir 1-1/2 cups cheese into broth mixture; cook over low heat until melted, stirring frequently. Stir in salsa and chicken; heat through. Ladle into bowls; if desired, top with sour cream. Sprinkle with cilantro and remaining cheese.