How can i reduce the file size of my images in Pages on my iPad?
Best is to reduce the photos before they are added to Pages. 

For printing they do not have to be more than 300 dpi. 

For viewing on the screen about 75 - 100 dpi. 

Pages doesn't do the job as you found out. 

You can do it in Preview > tools > Adjust size (on a Mac)

If do not ant to leave the iPad then you can use one of the many external apps to do it.

Simple Resize (Free)



or Image Resizer+ ($0.99)


  
  


Additional Info:

The Resolution has the biggest impact on the file size, not so the size of the image.