where (have) you been keeping yourself meaning

• [American slang]
  interrog. “I haven't seen you in a long time. Where have you been?”
  • Long time no see. Where've you been keeping yourself?
  • I haven't seen you in a long time. Where you been keeping yourself?
  
  

• where (have) you been keeping yourself?:    [American slang]In ...
• where (have) you been hiding (yourself)?:    [American slang]Go ...
• (have you) been keeping busy?:    [American slang]In ...