Once you 'clean' your VINYL many times it will be dull or look dried out , You can use clear majic or clear Amour all ,But your just going to be reapplying these products again and again , I personally would redye the headliner and the key is to use the correct dye and use very light coats . you will see by using very light coats it will give you that nice semi gloss look ,if you try to use dye the same way you would spray paint you will even with dye end up with a finish that looks painted and to heavy coated and that looks shabby think dusting coats not trying to cover with a wet coat as you will fill the grain of the material and end up with a shiny finish =bad !, Always when working with dye LESS IS BETTER ! I have used SEM coat products for many years with great results . You can recolor door panels,dash pads and even seats but in those "high traffic " areas you would want to use an adhesion promoter called BULLDOG , It comes in rattle cans or by the quart/gallon and again a little goes a long way MORE IS NOT BETTER ! AS WITH REFINISHING ANY SURFACE PREPERATION IS THE DIFFERENCE BETWEEN FAIR AND FANTASTIC RESULTS , PREP,PREP,PREP AND THEN PREP AGAIN !
Just remember once you wipe VINYL with lacquer thinner it will remove the finish and become permanently dull until redyed with VINYL DYE
As a side note many guys have jet skis that the top dash has faded and looks bad you can refinish them easily by wet sanding the plastic dead finish off down to good clean color and after cleaning the surface with Lacquer thinner and lint free cloth use a few light coats of Bulldog adhesion promoter as a clear coat and it will look brand new without buying a new dash cover ! try it, it really works I've refinished dozens that way