This is not a straight forward question in a sense that there is no data or evidence to guide your decision. Nothing but expert opinions.

The fact that she had an improved EF is reassuring, but her risk of relapse remains higher than the general population.

Termination of pregnancy will not prevent this replase. So that will not be recommended unless of preferred by the patient.

You are forced to stop ACE/ARB and spironolactone. You can continue beta blockers (perhaps switching to a more cardioselective agent like metoprolol succinate will make sense - again no data to support)

I would not recommend vasodilator therapy like hydral/ISDN unless needed to control high BP.

Counseling is key. Knowing the risks before getting pregnant is important.

No strong data to support stress test to check for contractile reserve but in my opinion will not be useful in this scenario. I would not recommend getting one.

An absolute must is involving MFM, high risk OB and planning for delivery location, mode, timing and preparation for mechanical support if she progresses to shock peripartum.

Baseline echo with strain imaging and serial echocardiograms every trimester for the 1st 2 trimesters and monthly in the 3rd trimester or at anytime if HF symptoms start to occur. BP and blood sugar control needs to be strict.

And hope for the best....

She is someone who will benefit from bromocriptine therapy after delivery (more data to come on that in few years we are part of a RCT to study bromocriptine in peripartum cardiomyopathy)

I hope this is helpful