Hygrophila Carombosa 'Aroma' question

The inevitable has happened to my Hygrophila Carombosa as it changed from
its marginal state to its submerged state. All the larger leaves have died
off and I'm left with a few puny stalks with small leaves being produced
that eventually break off. Some the stalks disintegrate and lie just below
the surface. They seem to be still alive.

What is the best way to treat this plant so that its submerged state is
attained quickly and so that I have a good, strong growth.

Thanks in advance