We are getting asked this a lot and without revealing the sex we don't know what we need! So jumping in for any ideas!
Atm only a few things...

Another monitor as DD will keep the movement monitor for her breathing until she has grown out of her lung issues
Some hooded towels

What we have and are doing...

We are keeping the same pram, and I have a "few" carriers (another carrier-a-holic here )
Borrowing a Bassinet then when bubs is ready for the cot transferring DD to a bed, she is int he cot set up as a toddler bed atm.
Hiring a cupsule, then when bubs is too big for that buying DD a Maxi Rider and bubs will get her Meridian.
Got a swing already
Plenty of wraps, maybe just a few new stretchy one's
Bought a few new items of clothes
Bought some new BPA free Bottles JIC but have the receipt in the box hoping to return them

If you have two in cots you would probably do with some more sheets, blankets etc