You guys have given me such good advice, I'm back for more. Hopefully you haven't been asked this a million times before.

I raised my existing floor (concrete slab) 2" higher to insulate it, using 2"x4" sleepers and plywood.

Problem is, the closet flange of my powderoom toilet is now 2" lower than the new floor. What's the best way to fix this?

The existing flange is black plastic (and is roughly at the level of the concrete pad). The 3" waste pipe is also black plastic (ABS, I guess).

Spacers? Cut out the old one with a dremel and cutoff wheel? (I'm not sure I have enough clearance to solvent weld a new one in with a 6" throat.) Or is it possible to weld on a new flange to the existing somehow? (I'd rather not choke down the 3" diameter drain to 2".) Something altogether different?

Any advice will be much appreciated. I have a graduation party for my daughter coming up in a month and the pressure is really on from my little bride!