Yeah, I've been there, been using DXM on and off since 96, and for awhile there there was really no point in doing it other than habit and desperation. I took a few years off, and then came back in a slightly more responsible way and these days:
After a month or two of staying away from dissociatives I have the option of one or two decent (and often earth shaking) trips at slightly higher than common doses. There isn't any point in doing anymore these days as the magic goes away quickly and I'll just be left in a boring, disappointing stupor that leaves me feeling stupid for days. I'm lucky, some folks don't get that.
Hope it helps.