As far as i think, the institute will not ask for any additional sum for postponing the exams. The exams would be held, but only on a later date. Since the students have already paid their exam fees, they will not ask for any additional sum for conducting the exam on a later date. The online exams like CP2, CP3 may not be postponed, but written exams will be postponed if things do not get better with regards to corona.
As GOFS03 stated, SOA and CAS have cancelled/postponed their spring exams. We can expect an update from IFoA anytime now. On the bright side if the exams are postponed, students get more time to prepare better. However, on the safer side, it is better to keep a good attitude and keep on preparing for the exams. The faster the virus came, the faster it may disappear as well. So not to have any sudden surprises, it is better to keep preparing and giving it our best regardless of what is happening in the world.
On it's website IFoA has mentioned that they 'don't intend to cancel the exams', so regardless of what happens, the exams will be conducted, but may be on a later date.