Looking at a random date in May (May 15), could be a challenge. The only practical train is a TGV from Gare Montparnasse station at 6:35 pm to St Pierre des Corps, connecting to a train to Amboise, arriving at 8:17 pm.
So that gives you 1 hour to get from Gare du Nord to Gare Montparnasse. They are connected by the No 4 Metro line, but there is still a bit of walking on either end. RATP suggests 5 minute walk from the platforms at Gare du Nord to the No 4 line platform, and 7 minute walk on the other end. There is a moving walkway part way from the No 4 platform at Gare Montparnasse, but you have to plan that it might not be running. It happens. So over all, it can be done in 30 minutes. 5:35 pm could be rush hour in Paris, so a taxi might even be worse.
If you miss the 6:35 pm train, there is one at 7:35, but with the connection at St Pierre des Corps, you would not get to Amboise until 9:17 pm, probably too late to get to your lodging by 9:30 pm. In that case, since you arrive at St Pierre des Corps at 8:39 pm, you could take a taxi from there. It is not too far, only 10 minutes on a train, so a taxi could get you there in time, if for a bit more money.