How do I get enough exp to upgrade gear?

I played the crap out of Reach when it first came out, so now my exp meter does not go up as much. But I accidentally deleted my save file a couple of months ago so I could fit in Mass Effect DLC. Now my entire armor selection is back to default. Is there some quick (legal) way to get exp in the game so I can get my armor back to what it used to be?

Nope, otherwise I wouldnt have had to reach Inheritor twice so badly. But even if you delete your save file, you can’t really do so without fiddling with your Gpd, and even if you deleted that it would update automatically once again as long as you were connected to Xbox live.

Do challenges and matchmaking I found to get exp the fastest.

Challenges and matchmaking will gain you credits the fastest.