You cannot increase the runtime to more than 15 minutes.

The AWS Lambda limit page states the Function timeout is 900 seconds (15 minutes). If you need more than 15 minutes of execution time you have to look at other services. You could have a look if AWS Batch would suit your needs.

Updated: The limit was changed from 5 minutes to 15 minutes.

Of course you can. My solution is:

1. Track time elapse in your lambda function
2. When it about to exceeds the limit, send a notification to SNS topic, then exit.
3. Set the SNS topic as trigger to your lambda function.

Keep in mind lambda's original purpose is to run short task so it's better to keep your lambda function run within 15 mins.

Now you can run AWS Lambda up to 15 minutes!

https://aws.amazon.com/about-aws/whats-new/2018/10/aws-lambda-supports-functions-that-can-run-up-to-15-minutes/