Technically? Yes! Incoming gravitational radiation of precisely the correct shape will in fact un-decay a orbit under exactly the same (modulo appropiate symmet

Technically? Yes! Incoming gravitational radiation of precisely the correct shape will in fact un-decay a orbit under exactly the same (modulo appropiate symmetries) circumstances as a orbit would decay by emitting (the reverse of) that radiation. (The same applies to thermal radiation cooling things off - see Liouville's Theorem.) For practical purposes, that'll never happen, but for practical purposes gravitation radiation doesn't matter anyway.