Utilize the presence of competitors as leverage in your negotiation with Forescout. Highlight specific offers from competitors to push for a better price or more favorable terms, reinforcing the notion that if Forescout cannot meet your financial requirements, you will have to consider those alternatives.
Push back on any proposed uplift in contract pricing by stating that your budget does not allow for it and that most of your suppliers provide better pricing models as usage grows or remains constant.
Given that your organizational needs may have changed, argue for a reduction in scope which directly corresponds to the budget constraints set by your finance team. This can help maintain costs, especially if you've not used the existing extent of services.
Emphasize that discounts previously offered should not be categorized as one-time unless specified in the contract. Argue that your finance team has budgeted for a standard pricing scheme.
Address potential overage fees by referencing the original agreement. Discuss that if these fees are implied, your expectation is for them to be waived given your commitment to moving forward with a potentially reduced scope.