Old rubber tree

[Richard Mersch]

My wife has had a rubber tree for about twenty years.  It's now about seven
feet tall and appears fairly healthy.  However, last year it did not fill
out as well as it usually does in the summer.

It's obviously root-bound, and we have ordered a larger (30") pot to allow a
transplant.

Can anyone give us advice as to anything else we should do for this old
friend?

TIA.