This article provides information related to the Auto-Connect feature in Juniper Secure Connect.

Once the Juniper secure connect agent established the remote connection to SRX after some time if the connection got disconnected is there any way to re-establish the connection without entering the credentials.

Juniper Secure Connect is a highly flexible SSL VPN and IPsec application that gives remote workers secure access to corporate and cloud-protected resources, providing reliable connectivity and consistent security to any device, anywhere. Juniper Secure Connect is available for desktop and mobile devices including Windows, Apple macOS, iOS, iPadOS, and Android.

Currently, the Juniper Secure Connect doesn't support auto-connect without entering the credentials.

https://www.juniper.net/documentation/us/en/software/secure-connect/secure-connect-user-guide/index.html