> How can I mirror the remaining links WITHOUT having to 
> download the link I already did, and have everithinh 
> mirored under the same "url".

Interrupt (gently) the mirror, waiting for pending 
transfers to finish, change the miror scope, and re-run the 
session using 'Continue an interrupted mirror'. Existing 
files will be rescanned (it can take some time, but it 
should be rather fast) and the rest should be downloaded.