I think it is permissible. It is not necessary that Jayachitra has to stick to MS-51 only. The course can be changed by not taking re-admission; instead by taking the route of re-registration to a new course.
The concept of change of course is applicable when a student has registered for the maximum of four courses (or less number of courses) in one semester and then desires to change one or two out of them in which case the rule is :-
"Change of Courses: A learner has to indicate in the Admission Forrn/Re-registration Form, the courses he/she is opting for. However, request for change of courses will be entertained within one-and-a-half month of the commencement of the session (i.e. by 15th February and 16th August for first and second semesters of the year) on payment of a fee of Rs. 1000/- per course through Demand Draft drawn in favour of IGNOU payable at the city of the Regional Centre. The application should be addressed to the Regional Director, IGNOU Regional Centre of your region."
However, in the case of Jayachitra, the validity of the registered course has already expired and it is not necessary that the same course should be opted for 're-registration'. The specialty of management program of IGNOU is that you can take any number of courses (subject to the limit of four courses per semester) during the validity of your registration. This enables you to do MBA (with one specialization stream), and all the PGDSMs if you so desire. However, the MBA specialization will depend on the first course from the specialization area you chose to re-register.
So I believe there is no embargo on choosing another course from Operations Management. However, I strongly recommend if Jayachitra can visit the study centre once and discuss the issue with the coordinator.