In a project named by "Emergency Repair of 11KV Cables", we have to attend the faulty cables between the substation to feeder. There is no testing in between the stages of cable jointing.. After charging the line, we come to know the performance of the cable jointing..

My question is :

It is a special process which can be validated at the final stage. So,whether we have to meet the requirement of 7.5.2 ?
Note : Cable Jointers need a special training as per contract requirement.

I think you can answer your own question. 7.5.2 says that any process in which you cannot tell the outcome from normal testing and inspection (special processes) needs to be validated. Does this fall into that category? Can you tell the quality of the joint from inspection and testing? Is applying power and confirming that it works part of the testing. Is there enough inspection and testing possible to tell if the joint will hold up over time?

I don't know enough about your trade to answer that, but I suspect that it is a special process. Evidence that you have trained the technician on the intricacies of this art of cable jointing could very well be part of your validation, just as training and certifying welders and solderers.

...any process in which you can not tell the outcome from normal testing and inspection (special processes) needs to be validated...
Emphasis mine...