Perhaps start with just DAYSTOREPAIR change:

# How many days of data do you want to keep?
DAYSTOKEEP=365

# How many days of data do you want to repair?
DAYSTOREPAIR=365

# You can override the above settings in:
source /etc/nsm/securityonion.conf

##############################################
# No need to change anything below this point
##############################################

# Check to see if there is a valid DB.  If not, exit silently.
if [ ! -d /var/lib/mysql/$DATABASE/ ]; then exit; fi

KEEPDAY=`/usr/bin/mysql -u$DB_USER $PASSWORD_OPTION -BN -e "SELECT
DATE_FORMAT(DATE_SUB(NOW(), INTERVAL $DAYSTOKEEP DAY), '%Y%m%d');" -D
$DATABASE`
REPAIRDAY=`/usr/bin/mysql -u$DB_USER $PASSWORD_OPTION -BN -e "SELECT
DATE_FORMAT(DATE_SUB(NOW(), INTERVAL $DAYSTOREPAIR DAY), '%Y%m%d');"
-D $DATABASE`

echo "Retention policy set to $DAYSTOKEEP days (deleting data prior to
$KEEPDAY)."

# Define a cleanup function
cleanup() {

        for TABLEPREFIX in "data" "event" "icmphdr" "sancp" "tcphdr" "udphdr"
        do
                /usr/bin/mysql -u$DB_USER $PASSWORD_OPTION -BN -e
"DROP TABLE $TABLEPREFIX;" -D $DATABASE
                TABLES=(`/usr/bin/mysql -u$DB_USER $PASSWORD_OPTION
-BN -e "SHOW TABLES LIKE '$TABLEPREFIX%';" -D $DATABASE`)
                for TABLE in "${TABLES[@]}"
                do
                        TABLEDAY=`echo "$TABLE" | awk -F_ '{print($3)}'`
                        if [ "$TABLEDAY" -lt "$KEEPDAY" ]
                        then
                                /usr/bin/mysql -u$DB_USER
$PASSWORD_OPTION -BN -e "DROP TABLE \`$TABLE\`;" -D $DATABASE
                        else
                                [ "$TABLEDAY" -gt "$REPAIRDAY" ] &&
/usr/bin/mysql -u$DB_USER $PASSWORD_OPTION -BN -e "REPAIR TABLE
\`$TABLE\`;" -D $DATABASE
                        fi
                done
        done

Published:
http://blog.securityonion.net/2013/12/bro-22-and-elsa-15-packages-now.html