Leather polish? Well if you want to go for a light draw you could go that way. Give the strop a base of dye in the right colour, polish with shoe polish and give it a few coats of leather sealer. heard good things about this sealer
Tandy Leather Factory - Fiebing's Acrylic Resolene but haven't tried it myself. I use a locally made product.
For a heavier draw I would use a wax based leather treatment, applied thinly and buffed off. Repeat.
Have a look at the Jay-El product line
Saddle & Harness Care: Jay-el
Mick