1. A method implemented by a computing system in response to execution of program code by a processor of the computing system, the method comprising: receiving, from a planning application, a spreadsheet including a plurality of values; presenting the plurality of values; receiving a first instruction to change a first value of the plurality of values to a second value; in response to the instruction, presenting a visual indication in association with the second value, the visual indication indicating that the second value is a fixed value; receiving a second instruction to refresh the spreadsheet; and in response to the second instruction: determining one or more of the plurality of values of the spreadsheet, each of the determined one or more of the plurality of values presented in association with a visual indication indicating that the value is a fixed value; and transmitting the determined one or more of the plurality of values and a request to refresh the spreadsheet to the planning application.