Need the original database. Revit doesn't let you switch like CADmep does. Why did you create a new one?
Once you have a DB, it shouldn't ever be thrown out...it stays even when you update software.
The only real reason to throw out a DB and start a new one is if the old one bad.
How closely do the 2 align? Are the ITM's named/organized the same? Fittings the same? IF the DB's are not closely aligned, there are some very poor, time consuming options that will likely take longer than just redrawing.