I seriously doubt the plane is too heavy. If the advertised specs are correct, then the Dolphin has a wing area and overall wing loaded right in between that of a Sig 4-star and a Goldberg Tiger-2. It should slow down and land very nice. Even the addition of different gear, glue from repairs and other stuff shouldn't hurt it too bad.

The GP Cherokee has a little less wing area and weighs more but it still lands nice, easy and pretty slow. Heck, My kit built GP Super Sportster 60 is a porker compared to modern ARF's. It has a wing area not much bigger than the Dolphin but weighs considerably more. It still has great low speed characteristics and lands nicely.

What is your plane doing at low speed? Nose dropping rapidly? Nose up (ballooning)? You may have a CG problem. Start with what the manual says but don't trust it. The technical information that comes with the no-name ARF's is very suspect. It should glide in at idle just fine unless you have a really strong headwind.