Y.M.
Hi,
I am a mom of 3 girls ages 15, 17,and 19.So it has been a while since I dealt with theses situations but one thing I did with my girls was to wear them out with activity they could handle at their age. If she still naps, leave the activity for later in the day so she will be tired at say 8:00 pm. The other thing I did was let them cry a little bit until she learns she can go to sleep on her own, the thing with this is my girls were a lot younger when I started this and I don't know how this would work with an 8 month old.
Activities you might want to try are if she crawls, go tothe end of a room and make her crawl to you holding a toy she likes, she can sit and bang on some toy like a xylophone, drum, etc.Whatever she likes to do that involves physical activity. Hope some of this works.