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These websites are a great resource, and contain many wonderful ideas. Let your girls use them as a starting point to plan their own ceremonies.

Ceremonies compiled by Neil Savage
Ceremonies and Awards on the Scouting for All Seasons website
Ceremonies from Village Trails Service Unit
Ceremonies from the Catawba Valley Council website
More ceremonies
Scouting Web's page of Ceremonies

Girl Scout Leader Center Ceremonies

Suggestions for an out-of-the-box rededication ceremony, from another Juliet:

Go to a Renaissance faire or SCA event and get "knighted" into the Order of the Trefoil by the reigning noble.
Go to a Senior center and see if you can find a very old Girl Scout to do
the ceremony for you.  Make sure you combine this with service.
Have your ceremony at a campfire, with or without camping.
Have the ceremony in conjunction with marching in a Veteran's Day Parade.
Once the girls have a general idea of where they will be and what they
will be doing, they will be able to figure out the details of the ceremony.

A ceremony for graduating Seniors