An increased approach speed comes natural if you think about it. Heavy rain influences the airflow over your wing quite a bit, thus increasing your Vs.
This of course also results in a longer landing distance, in addition to the fact that braking action is reduced. That's why a rwy may be good to use when dry but off limits in contaminated conditions.
Also (if your acft has it at some point in your career), obviously max use of reverse thrust is helpful.