You can use a good impregnating agent such as Sprayhood & Tent Protector to make your tent awning perfectly waterproof again. This impregnating agent is very suitable for most well-known brands of tent awning, such as Dorema, Ten Cate, etc. These types of tents are often made of Ten Cate All Season tent cloth, or cloth of comparable quality.
We developed Sprayhood & Tent Protector especially for impregnating camping tents, boat covers, sun canopies and catering umbrellas. We have been using it for years to impregnate and waterproof this type of tent cloth.
For more about impregnating tents, please see http://www.ultramar.nl/tents/tent-impregnation/
To: Sprayhood & Tent Protector impregnating agent