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Would reapplying next cycle significantly decrease my chances for those schools that reject or waitlist me this cycle? Even with say, a significant increase in my LSAT to land 170+ and some work experience? I know some schools like UPenn explicitly says that reapplying without significant difference would be penalizing. I guess high jump in LSAT score may fall under that 'significant difference'?

No, there is no decrease in chances by reapplying. Reapplying with a higher LSAT and more work experience only increases your chances of acceptance.