You can now use ElastiCache data migration feature to migrate your data from self-hosted Redis on Amazon EC2 to fully-managed ElastiCache cluster-mode disabled configuration. With this feature, once you provide ElastiCache-accessible endpoint and port of your Redis cluster, ElastiCache will replicate the data from your cluster in real-time to your ElastiCache cluster. Once the data sync is complete, you can update your client applications to start using the newly-populated ElastiCache cluster. 

from Recent Announcements https://aws.amazon.com/about-aws/whats-new/2019/10/amazon-elasticache-now-supports-online-data-migration-from-redis-on-amazon-ec2/