If you have a show next week and she’s 6 ounces overweight then your chances of her meeting weight are pretty slim. You can reduce her pellets and push a lot of hay. Also encourage her to run around. Depending on the judge, they could allow 1-2 ounces over without her being DQ’d, but it’s up to the judge (assuming they weigh her).
Some Holland lops don’t get the dwarf gene in which means they are not fat but actually just have a bigger bone structure. They are called normals. If it is a normal I would recommend just not showing it. But first make sure it’s not just over weight.
Is she fat or just over the weight limit? Some holland lops are structurally too large (they don't get the dwarf gene, and end up weighing over 4 lbs, often 4.5-5 lbs). Yes, they would be DQed at shows, but you wouldn't want to diet the rabbit and make them lose more weight than is healthy to get them under that limit. If she actually is overweight (check her shoulders - when they are overweight the first place you notice fat build up besides the belly is over the shoulders. Usually if you can't feel any fat there, they are a good weight) then the best way to diet her would be to reduce her pellets just a bit and slowly reduce her weight down but in that case you also likely wouldn't be able to get it down before the show.