Dear Aric,
Are those 2 similar lisitngs? If that's the case, you can do the following:
Whenever you receive an inquiry or booking, make them a special offer for your not-so popular listing. You can even offer them a discount and explain the reason (one lisitng has better position in the search results, due to more reviews, higher conversion rate, more views etc.).
If it is 2 different listings, Ï would try to lower the price of the least popular one to receive the first reviews. IF these are good, you can increase the price!
I hope that this information will help you!