I'm going to add another roll of cable to my manual cannon downriggers to get more cable retrieve per revolution and want to know the best way to do so. I've read that the Albright knot is the knot of choice because it will pass thru the roller if I happen to reach that point. Are there other alternatives to achieve the objective? Any tips and/or suggestions would be helpfull.

I think your cable retrieve/ratio would be minute at best. Personally, I would not splice. That will set you up for more frays and kinks in your cable and may cause a jam lowering. You'll be better off spending the money for a larger spool of wire

Downriggin'

Never splice downrigger cable, just buy a larger spool to put on it, you are just asking for trouble. Never step over a dollar to pick up a dime.
Peace Superfly