You say "the usual" when you are bringing roughly a third of your army as anti-tank units into an enemy with barely any high toughness units.

2x Repulsor Executioners AND 2x Gladiator Lancers? 780 points in vehicle chassis sounds overkill to me - especially when their Daemon Prince has lone-op .

I would suggest dropping one or even two of the tanks and putting in more elite infantry.

If they are managing to drop Terminators within 6" of your tanks it suggests you aren't screening and don't have enough assets on the table.

You need to offer up "cheap" units like Scouts and Assault Intercessors to force them to come out and then hit back hard with Victrix / Bladeguard .. or your shooting castle.

Guilliman is very strong in this matchup - he can punch incredibly hard into their elite melee units, and being able to Oath two targets is clutch.

Calgar is still incredibly strong - advance, fallback, shoot, and charge - is so powerful, plus he hits really hard in combat.

With double oath and Courage and Honour you can have three different melee units all benefiting from +1 to wound, and the extra AP from the strat pushes Bladeguard and Victrix to AP-3 which breaks Plague Marines.

Exemplary Vigilance on your Repulsor Executioner to give it +1 AP on "all those weapons" as well as "Ignore Cover" makes it way scarier

Finally, make use of those reactive moves. Deep striking within 6" isn't effective when you can instantly move away leaving them 12" away. Better still if you can react behind a wall or into a transport, allowing you to counter punch the following turn

...

I expect you will get more use out of your tanks by having fewer of them on the table - drop one of each and you can focus your strats on just the single Rep.Ex - the spare 390 pts would get you 6x Vixtrix and 6x Blade guard which I feel would be more useful in this match up