I have just emptied my sand substrate tank and went with aqua soil and increased my lighting too.
40 uk gallon tank, with sand substrate was fertilised and with c02 however, I let the tank lapse and stopped ferts, stopped co2 and cut the lights back, lace plant went dormant.
Having recently redone the scape, used A S as mentioned etc kicked the co2 back on and with water column ferts the plant has come back and is thriving.
Although, the bulb has pretty much rotted, I chucked it back in the tank anyway, and is doing well and looks like the crown could be split into 2 aswell.
Anyway, the point of that is, that in my experience, when this plant goes dormant, you can leave it in situ and upon change of environment it should just spark back into life.
Of course, there may be other scenarios but that is how it worked for me