There are two ways of updating the BLAST databases that come installed by default in the BLAST AMI:

1. Restart remote-fuser

Login to the instance and issue the following commands when there are no BLAST searches running on your instance:

/sbin/ --stop
/sbin/ --start

This will discard the already downloaded BLAST databases and switch to the latest available BLAST databases from NCBI.

2. Restart the instance

Stop and re-start the instance.