Extending L visa

Hi,

So I have a 3-month tourist L which will expire in 2 weeks but I want to stay here a bit longer. First I was thinking of going out of China and applying for a new tourist visa there, but then I learned that I can apply from inside China. I was wondering if this is still available and what are the chances of me being rejected to extend the entry permit for one more month. Thank you!

Lena