how to open a gnome terminal to execute a command with gnome-terminal, constantly?

Your command works fine but the gnome-terminal closes after the somecommand terminates, the reason being gnome-terminal not running the bash as it's default shell.

To get the bash prompt($) after the command command completes, you need to trigger it back.

-e "bash -c ./somecommand;bash"\

-e has since been deprecated. Use gnome-terminal -- somecommand now.