Back in 2006 India decided to upgrade its 52 (now 49) Mirage 2000 fighters, at a cost of $35 million each. The upgrade is still not complete and the cost has grown to $45 million per aircraft. Part of the delay was due to Indian insistence that most of the work be done in India. That meant Indian technicians had to be trained, often in France and special tools and equipment had to be obtained from France. The Indian military procurement bureaucracy is famous (or infamous) for its sloth and inefficiency and that has been a big part of the problem with getting the upgrades done.
Another example of that is the inability of Indian procurement officials to approve orders for spare parts for the Mirage 2000s, as well as for the items needed for the upgrades. Because of the delays in getting needed spares at least a dozen of the Mirage 2000s are grounded, some of them since 2010. It is also difficult to get politicians to agree on things like upgrades to older equipment, but the larger problem is the inefficient and often ineffective procurement officials.
So far two Mirage 2000s have completed the upgrade but are awaiting certification. That might take years. The Indian firm doing the upgrades say they can upgrade ten Mirage 2000s a year but no one with a knowledge of how these things work in India believes that.
The upgraded Mirage 2000s are getting new radar with 90 kilometers range (a 20 percent increase). The new fire control systems, modern electronic warfare systems and digital communications will make the Mirage 2000s capable of handling the most modern Pakistani and Chinese fighters. Other components (like the airframe and engines) were also to be refurbished. After the upgrade, the twenty year old Mirage 2000s would be good for another twenty. The upgrade price includes a supply of MICA, long range (50 kilometers) radar guided missiles which are similar to the U.S. AMRAAM.
While expensive, the upgrade would turn the Mirage 2000 fighters into long range air-to-air killers. These aircraft could very efficiently knock down their Chinese or Pakistani opponents (which are equipped with less capable Chinese FD-60 long range missiles.) Meanwhile Pakistan has received new F-16 fighters as well as upgrades for their older ones. Pakistan is al receiving American AMRAAM missiles as well. The Indians expect the French to provide electronic warfare equipment that can give AMRAAM a hard time. How well that works won't be seen until, and if, there's another large scale war between India and Pakistan. China uses copies of the latest Russian Su-30 fighters and the upgraded Mirage 2000s, as well as Indian Su-30s, are supposed to be competitive with those.