Multiple search/replace on pandas series
Create a definition for string replacements:

def change_string(x):
    return x.replace('|', '_').replace("elementary","elem").replace('old_value', 'new_value)


Then use map command to perform operation on entire column:

# You could create a new column to check whether the output is as expected
# If it is as expected, you could modify the original column
school_perf_report["SCHLNM_MODIFIED"] = school_perf_report["SCHLNM"].map(lambda x: change_string(x))


Hope this helps.