This is the 5658th most frequent Russian word.
прежней
"Прежней" means "former" or "previous" in English.
In this sentence, 'прежней' is used as an adjective in its instrumental case feminine singular form, describing the previous or former state of the work she continues to be involved in.
Она продолжает работать на своей прежней работе.
She continues to work at her former job.
Here, 'прежней' appears in the instrumental case feminine singular, relating to how the apartment's state or condition is no longer like it was previously.
После ремонта квартира не стала прежней.
After the renovation, the apartment didn't remain the same as before.
In this example, 'прежней' qualifies the noun 'однокурсницы' (classmate), denoting the former or previous association of the mentioned person.