i scored 97.1 percentile in 2018 slot 1 Cat exam. I am just one week away from cat, are there any chances that I will score above 98.5 percentile?

I would suggest you look at the actual score vs percentile of CAT'18 than going by Cracku's percentiles. Slot 1 of CAT'18 got down-scaled by about 3 marks on average. Adjust that and figure out your actual percentile. Next I'd recommend analyzing the test and figuring out where you could've scored better. Try avoiding silly mistakes and that'll give you some marks, also figure out which Easy/Moderate question you didn't attempt. Over all, you'd have a good chance of scoring anything between 96-98.5 depending on your temperament and on the above mentioned factors.

you will score perfect 100

congratulations