How to get a materialized view get to refresh itself after the job is "broken"

Question

we created a materialized view sometime ago with the following statement:
create materialized view SXV_PUB_EMPLOYEE_CERT_ALL_M
refresh complete on demand
start with to_date('30-08-2009 04:00:00', 'dd-mm-yyyy hh24:mi:ss') next trunc(sysdate) + (28/24)
as
select  sxv_emp_cert_all.*
from    sxv_employee_certification_all sxv_emp_cert_all;
this week we found out it had not been refresh for about a month
In dba_jobs the column broken was 'Y', next_date time something like 01-01-4000 and failures 16
when I ran it manually by executing
BEGIN DBMS_MVIEW.REFRESH('SXV_PUB_EMPLOYEE_CERT_ALL_M', 'C'); END;
I found that one of the columns was too small (probably a columns of one of the underlying tables had been extended since the creation of the materialized view)
After fixing this I ussied yesterday (on 29-8-2013) the statement :
alter materialized view SXV_PUB_EMPLOYEE_CERT_ALL_M
refresh complete on demand
start with to_date('30-08-2009 04:00:00', 'dd-mm-yyyy hh24:mi:ss') next trunc(sysdate) + (28/24)
after this the table dba_jobs showed me 30-08-2013 04:00:00 as next date
I was expecting it to run this night at 04:00, but it didn't
the last_date column value was still from about a month ago, the column broken still shows 'Y'
and the next date 30-08-2013 04:00:00 (while it should been set to 31-08-2013 01:00:00
Rrunning
BEGIN DBMS_MVIEW.REFRESH('SXV_PUB_EMPLOYEE_CERT_ALL_M', 'C'); END;
gave no errors this time
and in User_Mview_Analysis the last_refresh_date column showed the date/time I had executed it
Any idea how to get the job "unbroken" again so that the view refreshes itself every night?
the database is Oracle Database 10g Release 10.2.0.4.0
regards,
Remco

Answer 1

thanx for all your helpful and correct answers . but eventually I found it myself
exec dbms_job.broken(<jobnumber>, false);