I think it depends on what type of IPO’s you’re talking about, but I could be wrong.
I’ve only tested it with animation type IPOs like loc, rot, etc… Those keys in the IPO
editor are actual keyframes that can be viewed on the timeline of the NLA editor as well.
So, try this.
In one of the window section, change the little toolbar icon to the NLA Editor.
You should be able to see a list of all the objects in your scene along with all of their keyframes along the timeline. In this case, you could select all or some, then grab and move them over 1,000 frames (or however many you want).
I hope this helps.
Actually, I just tried it out again with other IPO. It seems to show keyframs for everything else in the NLA editor as well. So this should hopefully work for what you’re trying to do.