The book is available at Sacred Texts (I have not checked for other online sources). Here is the overview at Sacred Texts:
The Prem Sagar was one of the first books published in modern Hindi, written in the Delhi dialect which was eventually adopted as one of the official national languages of India. It is the tale of the deeds of Krishna, the invincible avatar of Vishnu. Based on the tenth book of the Bhagavata Purana, the Prem Sagar, which means 'Ocean of Love,' (one of Krishna's epithets) was composed by Lallu Lal between 1804 and 1810.You can find out more at Wikipedia.
Table of Contents
Preface
Chapter I
Chapter II
Chapter III
Chapter IV
Chapter V
Chapter VI
Chapter VII
Chapter VIII
Chapter IX
Chapter X
Chapter XI
Chapter XII
Chapter XIII
Chapter XIV
Chapter XV
Chapter XVI
Chapter XVII
Chapter XVIII
Chapter XIX
Chapter XX
Chapter XXI
Chapter XXII
Chapter XXIII
Chapter XXIV
Chapter XXV
Chapter XXVI
Chapter XXVII
Chapter XXVIII
Chapter XXIX
Chapter XXX
Chapter XXXI
Chapter XXXII
Chapter XXXIII
Chapter XXXIV
Chapter XXXV
Chapter XXXVI
Chapter XXXVII
Chapter XXXVIII
Chapter XXXIX
Chapter XL
Chapter XLI
Chapter XLII
Chapter XLIII
Chapter XLIV
Chapter XLV
Chapter XLVI
Chapter XLVII
Chapter XLVIII
Chapter XLIX
Chapter L
Chapter LI
Chapter LII
Chapter LIII
Chapter LIV
Chapter LV
Chapter LVI
Chapter LVII
Chapter LVIII
Chapter LIX
Chapter LX
Chapter LXI
Chapter LXII
Chapter LXIII
Chapter LXIV
Chapter LXV
Chapter LXVI
Chapter LXVII
Chapter LXVIII
Chapter LXIX
Chapter LXX
Chapter LXXI
Chapter LXXII
Chapter LXXIII
Chapter LXXIV
Chapter LXXV
Chapter LXXVI
Chapter LXXVII
Chapter LXXVIII
Chapter LXXI
Chapter LXXX
Chapter LXXXI
Chapter LXXXII
Chapter LXXXIII
Chapter LXXXIV
Chapter LXXXV
Chapter LXXXVI
Chapter LXXXVII
Chapter LXXXVIII
Chapter LXXXIX
Chapter XC
