Last year I queried Agent X, but ended up withdrawing the query when I embarked on a substantial revision. Agent X responded that they were going to request the manuscript, and asked to be informed when it became available.
While I revised, the agent changed agencies.
New manuscript in hand, I reached out to Agent X to ask if they were still interested. (I know you've said before to assume that the agent IS still interested, but due to the agency change the email chain was broken and I didn't want to send what might be considered an unsolicited attachment). I pasted in the original email chain and sent it to the agent's regular email address.
My conundrum: Agent X has separate query and contact email addresses. Should I have emailed the query address instead? How long I should wait for a reply before trying again at the query email address in case the email ended up in a spam filter? (Should I even do so? The new agency is a No Response Means No agency, but this wasn't technically a query, was it?)
You could actually be talking about me here since this is exactly what happened when I moved to New Leaf last summer. And yes that was a query.
Given the agent has expressed interest already, sending it to the direct email is probably the best choice. However, if you don't hear back, sending a query, mentioning her/his previous interest is a good Plan B.
If you don't hear back in a reasonable amount of time (60 days) chalk it up to changed circumstances and move ahead with your submission list.
Here's what you don't know: when an agent moves agencies sometimes the things s/he is looking to acquire also change. What I acquire here at New Leaf isn't based entirely on what I want. We also look at what the agency as a whole wants to add to our quiver, AND who else here is doing books in categories I'm also working in. In other words, Agent X might have a different set of acquisition parameters now.
What that means: QUERY WIDELY with this spiffy new manuscript. It's incumbent upon Agent X to reply to you in some sort of fashion or s/he's going to be out of luck when Agent NimbleToes signs and sells your work. And given I know your work, that's not some sort of pipe dream.