Hello, I'm not sure this will be useful to you now, but for anyone in dire need: there is a way to set your old house as your primary which will refresh it and make your new house enter the decay cycle.
I should offer the disclaimer that this worked for me a few months ago, but I am not in a position to verify that it currently works. However, I can't think why it no longer would.
You will need a house placement tool and funds in your bank to place a house.
The steps are as follows:
House (A) is the house you no longer want, which is on auto refresh. House (B) is the house you want to keep, but has entered the decay cycle.
1) Move your items from House (B) to House (A). Make sure House (B) is completely empty.
2) Stand under the sign of House (B). Say "I wish to resize my house" - this will demolish the house as described in
this link.
3) Place House (B) again. Your account has a one-hour reservation on that area, but try to place as soon as you can.
House (B)
should auto refresh, and House (A)
should be condemned and enter the decay cycle. Move your items from House (A) to House (B).
I used this once when I bugged and was able to place a house despite being on the 7-day cooldown, condemning my shiny new house. Because GMs can't help with house placement except to clear stuck items (soup, anyone?), I sincerely hope this isn't removed, as there are no contingencies in place to help when things go horrifically wrong.
Hopefully this helps.
(Edited for clarity)