If your unit economics have a CAC (Customer Acquisition Cost) Payback of 2 years it might be too long.
A good benchmark is to have a CAC Payback shorter than 1 year.
You might want to consider working towards a longer payback.
To do so consider reducing the cost of your Sales & Marketing spending and salaries. They can be found in the 'Expense' and 'Team' sections of your financial model.
Alternatively, you can try to increase your prices (ARPU; Average Revenue Per Unit/User/Customer) in the 'Revenue' section of your financial model. Be careful thought as this might increase your churn.
Remember, when you edit your numbers you should feel confident in them. You might have a reason for a long payback and want to keep it at this level.