Are there any known vitamins or shots I can get for my 3 year old daughter to prevent colds or boost her immune system to where she wont get as many?

No. There is no evidence that specific dietary supplements or medications will alter a child's frequency of colds or other viral illnesses.Kids between 1-5y are expected to get 5-7 respiratory and 1-2 other viral illnesses /yr. Kids in day care or those exposed to cigarette smoke often experience a few more.
Too many colds. Children get frequent "colds", 8-12/yr mostly viral. However, if more or severe infections especially with bacterial or "opportunistic" organisms see an allergist/immunologist for evaluation.
No magic pill. Many people are looking for some "magic pill" to "boost their immune system". There is no such pill. However, there is a way to boost your immune system, live a healthy lifestyle. Proper diet, proper sleep- wake cycles, healthy environment, proper exercise are the foundation of good health and good immune health. Supplements should be used selectively to supplement a healthy diet.