You do not choose who writes. You do choose whether the listing looks current.
Reply to what is already there. That habit, on its own, is associated in research with more reviews arriving later, because people see that someone is home.
Ask fairly for new ones: the same QR, the same sentence, no prize. Volume that comes only from 5-star guests is the volume Google does not want.
A single 2-star from last month, sitting alone as the only recent text, does more damage than the same score in a page that also has this week’s notes. More reviews will not save a bad plate. They will stop one bad afternoon from being the whole story a stranger reads.
Look at your listing the way a new customer would: last review date, last reply, mix of scores. If the last public word is from last year, that is the job for this week.