I think the most important first question to ask yourself is "has it been paying off for you in the past?" If you have been getting customers in the past from it (an older age bracket, local businesses looking for meeting space, local residents that need a place for family members or local businesses that host outside contractors ) then it continues to be worth the spend. May of the groups I wrote there can also find you on line, so you need to be able to qualify and quantify if the leads have been coming from the Yellow Pages. If, it hasn't worked for a while (and I suspect it hasn't been earning its keep if you're asking) then it's time to let it go.
If you do find you are missing a certain type of traffic that it gave you, you can always bring it back. But if you decide to let it go I would take that spend and direct it towards the type of customers you were hoping to reach in a type of outlet that those customers frequent.

Your marketing strategy and spend should be based on are you reaching the target audience via that channel? Is that channel relevant to that audience? If yes - continue. If not - find another channel to try. Hope that helps. I'd like to hear what you chose to do. Best wishes to you. Happy marketing.