Instead of creating new table delete all records from existing table and insert new ones. You may do it as a query:
1) Delete all rows
DELETE FROM YourExistingTable
2) Insert new records
INSERT INTO YourExistingTable (ColumnName1, ColumnName2, ColumnName3, ...)
VALUES (Value1, Value2, Value3, ...)
or
INSERT INTO YourExistingTable (ColumnName1, ColumnName2, ColumnName3, ...)
SELECT ColumnX, ColumnY, ColumnZ
FROM AnotherExistingTable