、。
Since there was no reply, I wrote to her again.
Literal
Reply [subject-が] didn't-exist [because-ので], I [topic-は] she [to-に] again letter [object-を] wrote.
再度 is a more formal/written synonym for 'once more,' compared with the everyday もう一度. Both mean 'one more time,' but 再度 (Sino-Japanese 再 'again' + 度 'time/instance') carries a crisper, businesslike tone — fitting for a context where the sender is reporting that they sent another letter after no response.