if your roof not in bad condition such as cracking etc, better repaint. For repaint old roof tile, to make your paint last longer advisable to remove the fungus on the roof tile first before (the fungus can be remove by spray water jet) repaint else the new paint will not stick long enough on the roof tile due to fungus. Id depend on the fungus on your roof tile..if not so bad then can repaint without removing it.

good luck.

Door shop at Poh Yep Kinrara..a lot of choice and reasonable price.