。
She kept crying all night long.
Literal
She [topic-は] all-night cry-continued.
泣き続ける ('keep crying') uses the productive aspectual auxiliary ~続ける ('continue doing'), attached to a verb stem. This contrasts in subtle ways with the related ~通す (do something through to the end): ~続ける emphasizes the ongoing process — she stayed in the crying state — while ~通す would emphasize that the activity reached completion through to the end. With 一晩中 ('all night long') setting the duration, the sentence captures sustained, unbroken crying.