If you have a Freighter, use that to warp to other systems (it can reach every star color by default, and usually does longer jumps compared to your average ship), then dismantle hyperdrive upgrades from your ship to get back that extra space.
About that, my starship's hyperdrive is upgraded to the point where it can warp 6 times as far as my freighter, but I have no idea how to upgrade freighter hyperdrives or if you even can.
So, I'm stuck in a water planet- no thruster fuel, no di-hydrogen to be found.
What do I do?
Usually astreroids spawn everywhere in space so you can just blast them to get Tritium which fuels your pulse engine. If that fails, look for a fleet of freighters orbiting the planet, land on one, and buy some Tritium or Di-Hydrogen from someone inside.