Night and day we pray most earnestly that we may see you again and supply what is lacking in your faith.
NIV
[And we] continue to pray especially and with most intense earnestness night and day that we may see you face to face and mend and make good whatever may be imperfect and lacking in your faith.
AMP
Night and day praying exceedingly that we might see your face, and might perfect that which is lacking in your faith?
KJV