I keep a spreadsheet with rep records calculated in 1RM. So for BP its currently 117,5kg x 6 = 136kg 1RM. Next time I do that lift my goal is to beat that, if thats eventually done by 112,5 x 8 or 122.5 x 5 doesnt matter, both will have beaten my previous 1RM.
I always set myself up for going for a PR prior to entering the weightroom. I know from experience some days are good and some days suck. If its a good day I go for it. If its a bad day, I know I´ll come back and beat it another day, and try not to let it affect me too much.