Answer:
She had not considered the connection between school uniforms and attendance. ⇒ Include a new subtopic or section in her paper.
If she had not considered that there might be another factor affecting her research, she can simply add a new section or subtopic where this new factor would be explored.
Her position has changed on the topic of school uniforms. ⇒ Adjust her thesis statement.
As her position has change on the topic, the thesis statement would need to be adjusted because that is where the researchers stance on the research is shown.
She realizes she is relying too much on the information of a single source. ⇒ Balance her supporting evidence from multiple sources.
She should look for information from other sources so as to balance out the evidence she has from that one source and make sure that is is accurate.