Keep other columns untouched

Question

Im trying to divide some columns by fixed number (1000) and remove commas, also change mix type into int with the second last code line. Except the list of columns, I do have other columns that are being deleted after executing the code. How can I keep other columns?

df_1 = pd.read_excel(os.path.join(directory,'copy.xlsm'), sheet_name= "weekly",header= None)
df_1 = df_1.drop(df_1.columns[[0,1]], axis=1)

df_1.columns = df_1.loc[3].rename(None)
df_1 = df_1.drop(range(5))
columns =["A","B","D", "G"]
df_1=df_1.loc[:len(df_1) - 2, columns].replace(',', '', regex=True).apply(pd.to_numeric) / 1000

df_1.to_csv(directory+'new.csv', index=False, header= True)