Help building a calculation or Point me in a Direction

I have a dataflow that is sourcing from an online dataset that updates daily. My dashboard updates daily and pulls in each of probably 4 or 5 different datasets all updating the same way. 

I have the below formulas built to calculate different things, but what isn't working is I can't find a way to get the previous day's data. Doing some research is what prompted me to build what I did below but it is not doing what I need it to do. 

What I am trying to do is pull in my data and update my visuals. The following day I want to pull in the same data, compare it to the previous day (eventually previous week/month) and then it should adjust the trend arrow accordingly up or down or dash if no change, and change the color. I'd like to eventually graph some data using this process. What I'm trying not to do is pull data daily and store it in a folder to continually reference it if I can help it. 

KPI Previous Day Remaining Items =

VAR PrevDayValue =

    CALCULATE(

        [KPI Remaining Items],

        DATEADD('Date'[Date], -1, DAY)

    )

RETURN

    IF(ISBLANK(PrevDayValue), 0, PrevDayValue)

KPI Remaining Items =

VAR Result =

    CALCULATE(

        COUNTROWS('MMIS Status Update'),

        'MMIS Status Update'[completion_status] = "Not Completed"

    )

RETURN

    IF(ISBLANK(Result), 0, Result)

date table:

Date =

VAR MinDate = CALCULATE(MIN('MMIS Status Update'[update_date]))

VAR MaxDate = CALCULATE(MAX('MMIS Status Update'[update_date]))

RETURN

ADDCOLUMNS(

    CALENDAR(DATE(2020,1,1), DATE(2030,12,31)),

    "Year", YEAR([Date]),

    "Month Number", MONTH([Date]),

    "Month Name", FORMAT([Date], "MMMM"),

    "Year-Month", FORMAT([Date], "YYYY-MM"),

    "Quarter", "Q" & FORMAT([Date], "Q"),

    "Week Number", WEEKNUM([Date], 2), -- 2 - Week starts on Monday

    "Day of Week", FORMAT([Date], "dddd"),

    "Is Weekend", IF(WEEKDAY([Date], 2) >= 6, TRUE(), FALSE())

)

Trend Arrow:

KPI Trend Arrow =

SWITCH(

    TRUE(),

    [KPI Remaining Difference] <0,UNICHAR(11165), // Down arrow

    [KPI Remaining Difference] >0,UNICHAR(11167), // Up arrow

    UNICHAR(9644)                                // Dash for no change

)

Trend Arrow Color:

KPI Trend Arrow Color =

SWITCH(

    TRUE(),

    [KPI Remaining Difference] >0, "Green",

    [KPI Remaining Difference] <0, "Red",

    "Gray"

)

KPI Remaining Difference =

[KPI Remaining Items] - [KPI Previous Day Remaining Items]