It's such a subjective situation that is based on your situation and the market down there.
Generally speaking, if you can sell and find a comparable property for less money (after closing costs and all expenses associated with selling and buying), or a better property for the same amount of money, then that's what you want to do.
Do you need capital or can you afford to leave your capital invested in this property? Is the market appreciating and if you sold it next year will it be worth more? Do you want to be a buy and hold or a buy and sell investor RIGHT NOW?
Also, I don't see where you're going to make 15-20K by selling this. If you paid 68K and put some time and money into already, let's say you're at 70K all day. You sell it for 87K and have to pay Realtor and other closing fees, amounting to, let's say, 10%, or about 9K. You're looking to make about 8-11K by selling between 87K-90K. Is it worth it? Ask yourself these questions and find out. :)
Good luck!