Will it be the same questions, or a different question bank? Do you know exactly which ones you got wrong and why? Is there a possibility of getting lower than an 88, and if so, will you get to keep the higher of the two scores?
I probably wouldn't retake it because I'm lazy, and an 88 is pretty good. But I would if I knew exactly which questions I had gotten wrong, and the question bank was going to be the same (assuring I would get a higher score).
FormerlyRR, in that case I'd be on the fence. The good news is that it almost certainly won't take you as long to retake it a it did to take it the first time. If it takes the highest score, then you have nothing to lose. Would a higher score have a big impact on your overall score in the course? Like, would it mean the difference between a B and an A?