Thats a great question, and not one easy to answer. Maybe you can figure out what you like about a given internship for starters. Is it the type of work? The culture and people? The hours, location, something else?
From there, you could apply to other internships and compare what you like about your current place vs what the new places offer.
Additionally, you could ask the existing internship if it would be possible to work in a different role or position, or expand your level of responsibility during a second internship.
Good luck.
------------------------------
Christopher Seigel P.E., M.ASCE
Civil Engineer
------------------------------