You mention the high and low spots, but there will also be tunnels - these are sometimes just about visible because of a raised ridge in the ground where they are. You really need a heavy roller; this should be rolled all over the lawn, which will compress the tunnelled areas and hills. This also makes the area safe from the point of view of walking over it - you won't finish up with your foot sinking 6 inches into a tunnel you didn't know was there. Once you've done that, examine the area again.
If you still have raised areas, you can either peel back the turf, remove some soil by digging, and replace the turf, or just shave the top off, and rake up the surface to make a fine tilth. With the lower spots, fill those in with good topsoil, preferably weedfree, until you have levelled the whole lawn area.
Broadcast (sow) grass seed over the deeper filled in areas, and any bald places where you shaved the top off. Areas filled in with less than half an inch of soil may not need seeding - the grass will work its way through, but deeper areas should be seeded.
The best time to do this depends on your local climate - in the UK, now would be a brilliant time because the soil is still warm, so the seed germinates quickly and will have time to be grown on well by winter. An equivalent time/weather period for your area would be best, but re-seeding can also be done in spring, though the seed takes longer to germinate then.
If you can't get hold of a heavy roller, the only other option I can think of that doesn't involve machinery is to walk all over the lawn, closely, on your heels, the way you do when you first prepare an area for turf or seeding.
If all that sounds like too much work, it might be marginally simpler to lift the existing grass, relevel all over, prepare the ground properly and returf (re-sod) - but it is only marginally easier. If the grass has a high percentage of weed invasion, including moss and weed grasses, with less than 30% being desirable grass, replacing the whole thing is probably be the best option.