My eight month old just wouldn't go to sleep....!!!

Olivia
My eight month of baby just wants to play and wouldn't go to sleep!!!! She used to be asleep by 8:30 but the past couple weeks she just wouldn't go to sleep!!! Is this going to be a phrase? What should I do? I have tried everything! She would fall asleep and 2mins later she's crawling smiling and playing with her blanket.