Don't worry, they are in terminal decline. They have lost Scotland, are losing Wales, and never had a foothold in Southern England. They pile up votes in post industrial northern cities but that will not be enough to form an election winning coalition of voters.
They have an incompetent leader, are fighting each other like rats in a sack, and their big ideas are to raise taxes and have unlimited immigration.
In fact most of their ideas are electoral poison.
Time for a reshaped left of centre party and some serious thinking about how to take the country forward in a "progressive" way. I don't see much of that anywhere and none of it on TSR.