[hitsurume]

Assuming you're in the position of power, you have to clean house in your company / department and weed out all the bad management / policies that drove people out in the first place. Then, you in theory will have a large amount of budget to work with (since people have left, and people have been fired/let go) and you can use that budget to incentivize good people to work there. Competitive salaries, equity, benefits etc. A lot of good engineers like small teams / companies because they believe they can make a bigger impact on the culture and direction of the company.