Importing/exporting data from (to) another Redis® database through Lambda Store console is a feature in our roadmap. Until it is released, you can use the redis-dump tool import/export data from another Redis.
The below is an example how to dump and import data:
> redis-dump -h <YOUR_ENDPOINT> -p <YOUR_PORT> -a <YOUR_PASSWORD> > redis-dump > dump.txt > cat dump.txt | redis-cli
See redis-dump repo for more information.
When import/export data feature is released, you will be able to import huge amount of data in a faster and more convenient way.