Reseal with 100% clear silicone caulk (yes the stuff in the tubes at the home repair center) - dissolve with mineral spirits (the real stuff, not the kleenstrip eco brand) - you're making a 'thick' of a liquid as you need for working with. The thinner the better - but too thin could be porous. You also have a very short working time so mix up a small jar/container and brush/roll/spray on (depending on the tools you have available) - you can also dredge/drip/soak but submerging the whole fabric...but this distributes silicone on both sides - and generally you want the inside to feel nicer. You can also respray with durable waterproofing sealants - which is basically the same mixture (dissolved silicone in a solvent). For the rips/cuts/tears...you should reinforce by resewing or patching and gluing. Most tears will get worse as wind and movement flex the material.