You have to have a target time, check your mile splits to see if your ok and push hard for the last 1/10th. It will certainly test your commitment. If you really are motivated to beat your PB, then you will do it.
If you manage to beat your PB, then you will get my vote. good luck
I have been a running coach for a number of years now. I have heard so many people say they are going to do this or that, but never follow through. How committed are you to breaking your PB? how many 5k races has it been since your PB? what training have you done in the last month?