Off the top of my head:
I think Fairplay was the only pre-All-Stars contestant asked.
Chris (Vanuatu winner) - not asked
Coby (Palau) - Another victim of the reduction from full All-Stars to fans vs. favorites
Steph (Palau/Guatemala) - Not approached
Jenn (Palau) - Approached but not sure what happened
Courtney (Panama) - Approached but not sure what happened
Shane (Panama) - Approached but not sure what happened
Candice (Cook Islands) - Approached but declined because of medical school
Dreamz (Fiji) - I know that he was considered; don't know if he was approached though
Courtney (China) - Approached but declined
Peih-Gee (China) - Approached but not sure what happened
They may not have asked anyone from Guatemala but I'm not 100% sure.