I am a 50 year old woman but I work with a lot of younger women. In conversations I use, "I know, right?", so often now that they make fun of me.
First of all, make fun right back at them. :)
It sounds like you're talking about a habit. I could throw a bunch of equivalent expressions at you to replace this with
You know it
but what might help you shake things up is to stop and think of something to add besides agreement. It sounds like you want to support what is being said. Take a moment to think of something new to add that is also supportive.
Or just tell them you're 50 years old now and you'll talk however you damn well please. ;)