refortify
verb
re·for·ti·fy (ˌ)rē-ˈfȯr-tə-ˌfī 
refortified; refortifying
transitive verb
: to fortify (something) again
refortified the castle
refortification
(ˌ)rē-ˌfȯr-tə-fə-ˈkā-shən
noun plural refortifications
refortification of the northern border
Word History
First Known Use
1579, in the meaning defined above