Many insurers are now offering double sum insured products where the insured can avail a higher cover at no extra cost, after exhausting the original sum insured.

The premium to be paid for a restoration policy with a basic sum insured of Rs 300,000 and the option of doubling it would be at least a few thousand rupees higher than a policy with just a basic sum insured of Rs 300,000.
Most of these policies provide the additional cover only when the condition is different than the one for which claim was made. For instance, if a diabetic with a Rs 200,000 sum insured policy exhausts it, following the amputation of a toe and then later develops diabetic retinopathy during the tenure of the policy, it will not be covered.
In a family restoration policy, if one member exhausts the entire sum insured, he cannot avail the additional coverage. It will only be available for another member of the family who is covered by the policy. If someone already has a policy but feels that the coverage is inadequate, he can go in for a top-up policy with a lower premium, which will be of use if the first policy is exhausted.
Source-Medindia