Yah, got many kind of these friends but most of the times they kena suan by me jialat jialat... heehee... erhhh.... in english its, they get rebutted by me in a very serious way. :p
Even those old aunties were rebutted by me and left me alone after that which is good for me.
How much do you value your friendship with this older girl? If you like her tell her nicely, If not then do like me, suan her until she see you also run away.

Or you can reply to her "Yah lah, yah lah, you're right, you're right" The more yah lah and you're right you say the more sacarstic you sound. Then if she is as great and smart as you say, she will stop lecturing you.
This doesn't work on stupid people though, it will only blow up their ego. Heh heh... now you know. Shhhhh.... don't tell people, okie?