"Upgrade" isn't very specific, so I'll try to answer.
If you need to build product, then you have to find developers to work on sweat equity, which is getting harder and harder and you may have to give up a big chunk of shares. Same if you need to upgrade your sales and marketing efforts. Find someone who believes in the idea and in you. Make sure to read Slicing Pie by Mike Moyer. Don't give up fixed chunks of equity.
If you need capital and can't raise money, then if you have a product or service to sell, focus on building revenues. That is always the best way to fund a company. Debt is always an option, albeit not one our spouses usually embrace.
Find another way to earn money. If you have skills that others would pay for, do a bit of consulting to pay the bills. Drive an Uber at night.
Bottom line, where there is a will, there is a way.
@Chicke is correct. It is not clear whether you are already operating and want to improve an existing business or expand its capabilities, or if you're hoping to launch a big idea but can't figure out how to fund more than a small part of it.
If money weren't everyone's problem getting started, you'd see a lot more things started.
What you must do before you move forward is planning and then validate your strategy. The goal of the planning phase is to determine whether your idea can be executed with the resources available, If not, you need to plan something else that gets you there or surrender to the reality that you do not have a good plan and should stop before you lose what money you have.
Most people don't want to give up on their ideas, I understand. Validating your strategy is the best way to protect yourself from predictable financial loss and emotional hardship. Sometimes the answer is no.
Considering that the likelihood of any business getting outside funding is about 5% (which includes bank loans and other non-investor measures), it's important to plan a business that can sustain itself and move forward without outside financial support. Almost all nascent businesses start with personal funds.
Your job is to figure out what you're doing wrong that won't generate the capital you need to grow/upgrade. That's the responsibility of the owner. Any more specific an answer would require detailed information about your business and an expert or two who can advise you further.