Why wont my 6yr old go to sleep???

My child has always been an awful sleeper.  Always waking up at night.  I have tried anything that anyone has ever suggested. Even tried a major bribe (buying her a cat if she stayed in bed for 3 months). That worked for about 6 months. Eventually, she started getting out of bed again....anywhere from one to six times a night. So, I kept threatening to take her cat away. I followed through.  Took her cat to stay with grandma until my daughter stayed in bed again. Life was good!
Now, here we are 6 months later. Now, she wont go to sleep.  Takes her hours, and repeated trips back to her room.  I have tried comfort talk, consequences, and even resorted to spanks.  Nothing works.
I dont understand this.  Her bedtime routine is consistant.
I honestly feel like Im ready to run! I cant take this anymore.  I wouldve thought that by the age of 6, she'd finally just sleep well.
What can I/we do????

[teddybears4ever2]

Does she have a stuffed animal?  Has she seen something scary that could keep her awake at night?  Does she have a nightlight?  Do you read to her at night, or sing to her?  Does she get up to pee or need a drink?  Have you taken her to a doctor about it, or a therapist?  Have you taken her in for a sleep study?  All of these could help.

[AnnieBrooke]

Does she get enough exercise in the daytime, so that she really is tired enough to sleep through the night?  Is there something in her life that makes her anxious?  Is this the only way to get your undivided attention?  

[eileenmargaret]

She sleeps with ten "babies". All placed just so on her bed.
She has a nightlight.
Her bedtime routine includes a book, incl cuddling.
I have actually book an appointment for this thursday with our family doctor to discuss counselling.....because I just cant figure it out! Its not good for her or myself!

[eileenmargaret]

She just started grade 1....but that shouldnt be a problem.  Her daycare is right in the school, so integration into JK and SK were a breeze.  Its just into another room. All the kids pretty much know each other.  
She is pretty active....although I took a break from martial arts this month until she settles down.  Not sure if that was a good or bad idea???
She gets alot of attention. When Im not at work, we are together all the time.  We go and do everything together. I def know she feels loved!
Im just not sure what else could be bothering her that much to make her anxious.....
I do feel as though its "seperation anxiety", but not sure what triggered it.