Lookup and re-write[update] the data for last 2 days

Hi All,

I have google analytics step, which extracts te data and table output step which dumps the same data into target mysql tables.
in between I have intermediate table which holds the data in it.these data will be fed to final target table as mentioned earlier.

As the last 3 days data including today's data is not consistent , i need to change[re-write] those data in target table.

I presently set a ${end-date} variable to todays's system date and and with the of modified javascript value i set previous 3 days date as ${start-date}.

Please let me know how do i need to update my target table without effecting other data which are older than 3 days[including present date]
How do i lookup and modify[update] the data keeping above mentioned points in mind.

Thanks in advance. I really appreciate your help/inputs.

Thanks,
Malibu