It very much depends on what the indemnity insurance covers.
Often such insurance is taken out to cover a �grey area�, where at some later date an issue may arise which could incur costs to rectify. Such an example might be where there is a question relating to a public right of way, or the design of building. Rather then spending loads of money sorting the potential issue for certain � an indemnity insurance is taken out to cover such an eventuality.
Normally the potential issue diminishes with time, due to time limits for objections etc. and therefore by the time you come to sell the property, no extension to the indemnity should be required.