New Tank

Broadly, that's exactly what you need to do. There are a couple of points to note.

You are, in effect, moving your tank and it's contents. It will finally end up in the same place, but I can play semantics with the best of them, so have a read of "Moving Your TanK". This will give you a good idea of what's going to be involved.

Remember, we cycle the media in our filter, not the tank. With that in mind, your filter may not be large enough for your new tank. You may have to replace it, or add a second supplemental filter.

I upgraded from a 125 to a 180 litre earlier this year. I used new sand and got a new, bigger heater but I moved the decor, filter and fish straight over, together with most of the water from the old tank. I didn't have any problems.
You will lose the bacteria on the glass itself (they grow on every surface, just more in the filter) and the ones on the surface of the substrate could end up buried. Keep an eye on your ammonia and nitrite for several days to be on the safe side, and do a water change if you see either of them.

With a bigger tank you'll be very tempted to get more fish, but wait till you're sure everything has settled from the move.