Shell Programming and Scripting

Folks;
I'm writing a shell script to extract some fields out of a log file & it will run periodically, how can i make it runs starting from where it left of. for example;

if the script will do the extract every 2 days, let's say the first run will extract fields until July 25, 2007 @ 11:15:22 pm
How can i make the second run start from July 25, 2007 @ 11:15:23 PM?

Here's the script:

#!/bin/sh

echo " field1 field2 field3"
egrep 'Real value' new.log | \
while read mLine
do
mFld1=`echo $mLine | cut -d'|' -f1`
mFld2=`echo $mLine | cut -d'|' -f2`
mFld3=`echo $mLine | cut -d'|' -f3`


echo "$mFld1 $mFld2 $mFld3"
done