Founder of 2 successful companies: Copy Power & Business Bitch
Former Chief Marketing Officer of app development company & startup incubator.
10 years of experience as professional writer
9 years of experience as online marketing & at making money online
If you're getting a lot of small jobs - congrats! That means you have a lot of customers who know your value and are willing to hire you.
That said, I TOTALLY get the desire to want to have fewer clients to manage, at a higher price point per project.
The first thing I'd have you ask yourself is this: Who are the people who would hire you for the kind of bigger jobs you're after?
Are they homeowners in more affluent neighborhoods? Development companies building new neighborhoods? Businesses who want their grounds to look nice for visitors?
Identify who they are, and put yourself in the same rooms as them. Find the kind of events they go to, and go to them to. Print of business cards that are more focused on the longer-term projects you'd like to have, rather than the smaller, one-off projects you're currently getting.
And leverage your testimonials. If you're continually landing lots of jobs, that tells me that people are happy with your work. If you don't yet have testimonials, ask your previous clients to give you some. Putting these on your website or on your other printed marketing material can go a LONG way in showing a new target market you're trying to break into that you're trustworthy and someone they'll want to hire.
Another reframe could be finding ways to make your basic analytics useful. If a subscriber sees a certain piece of data, what does that tell them they should do? Even the most basic data can be incredibly useful if paired with useful suggestions. I don't know much about your app, of course, but this is just a thought.
In the long-term of my business, by FAR the best lead generation strategy has been blogging. When I can write guest posts on sites my target audience already reads, those posts pay me back for YEARS because people read them, see them, and then click on my author link to get in touch with me.
On my own website, I do basic SEO to answer questions people are typing into search engines, and get a lot of client inquiries that way.
This strategy does take some time to build up, but without it I'd still be chasing job listings and be working in more of a glorified freelancer model, rather than as a full-fledged service business/agency.