How to get historical data if deleted accidentally from BW ?

Dear experts,

I have one basic query, Say I have loaded some data to BW today from R/3, after some months the data got deleted from BW accidentally, now how can I reload the same data if the data is not available in BW / PSA and I understand R/3 maintains only the recent OLTP data ?

Appreciate if explained in steps and will assign the points for the best answer.

Regards

Mohan