Practice not crashing the kite in the first place. In your lessons they may have said let go of the bar when you crash. That is means you are not doing the death grip and sending the kite into death loops. BUT if you keep your cool and concentrate on no flying the kite while you crash then you will be able to stop the kite crashing into the water 9 times out of 10.

If do need to relaunch fast. Try reaching up the leader line of the upwind wind tip and pulling hard. Then when you get the kite out of the water let go of the line and fly the with the bar as per normal.

When I crash I usually keep the kite out of the water but it's just sometimes when the wind drops off or whatever and the kite drops. I'm using a 2008 rebel and 2013 crossbow. I can relaunch it when waters not on it but when it gets covered in water and water sits in between the struts that's when I have trouble.

What technique are you using?
If you are just pulling a steering line to relaunch the kite, yes this will work in normal wind, but there are 2 other techniques I use to help me in light winds. Both of these methods assume the kite is directly downwind of you, with the LE in the water.
1. this is the easier one, you pull the one steering line and the opposite centreline as well. This will help the kite roll over easily. Once its on its side, let go of the centreline and walk it to the edge of the wind window like usual.

2. If you can stand in the water this one is really good in super light winds, but you can easily invert the kite if you do it wrong.
let go of the bar, and keep one steering line in your hand. Standing up, quickly pull hard on the centrelines then walk towards your kite. What this will do is make the kite roll backwards as if it will invert, at this point you want to pull in the steering line and the kite will fold/roll over itself and go onto its side. From here you would have stopped walking, and you simply walk the kite to the edge of the window and relaunch as normal.

Once you have these techniques in your quiver you will have a much easier time kiting in light winds. The second technique is a bit risky, practice it a couple times and once you get it you will be fine, out of me and my friends I was the only one who pulled it too hard and actually inverted the kite.

I will try find some videos for you to help explain it better

Out of interest, are you only having problems when the wind drops or more often? From my experience the Rebels aren't the easiest kites to relaunch when the wind is very light.

Jukesy,

How well inflated is your kite? I don't know what the 2008 Rebel is like but i have a 2012 12m and a 2014 9m and both re launch in the water really easy, as others have said, in lighter winds they can be a pain and take a little longer. Otherwise any decent wind and the kites ready to jump up.

Almost all my water re launches are done by the first method in those videos, pulling on one steering line to catch the wind, the kite then walks along the water to the edge of the wind window and then comes up.

As Just2807 said maybe have a look at your lines and trim the accordingly. Keep at it, perhaps instead of walking in next time you crash the kite, spend the time to move the kite along the water and really practice those water relaunches, they're a critical ability you should master.