Apart from attracting the Lankan diaspora to invest in specific projects and enterprises, I am skeptical that many would actually move back entirely, especially those who are younger and have more at stake. Except for a champion few who have moved back to launch path breaking initiatives since the end of the war.
HOWEVER, I think if we can mount a clever marketing campaign to attract diaspora retirees - Lankan diaspora members in the 55+ age group, I think we may be on to something. Most expatriates I've spoken to say they would 'love to retire in Sri Lanka', with a nice house by the sea etc. And having provided for their children and seeing them all settled down and financially independent, and also with a slight onset of arthritis (which is miserable when you're living in wintry Toronto) they are more likely to be wooed back to sunny, easy-living Sri Lanka.
We could start marketing the new Eastern beach fronts, and even some of the Negombo, Puttalam, Kalpitiya lands for retirees/holiday homes etc. But of course it's not just the land-by-the-sea factor. We need to open up more private participation in health care, so they know they should they need it they have access to super medical facilities; better transportation links; fewer bureaucratic burdens etc.