Non profit customers? Only a fool keeps customers for years with no profit.
The problem is not that they are 25 minutes away unless you go there everyday when you should be going there say 2 days a week.
No problem that they only want mowing and no up sell. Work is work.
The problem is with many Landscaper's is that they keep low profit margin customers just so they have enough work expand their business to a second route.
Then when they down size and go back to solo the say they are making the same money without the head aches and expenses of running crews.
The answer is to always cull out the least desirable customers before they realize that they are carrying so many bad customers.
As to your old town small yard customers. The problem is not that they do not want up sell's. Many Landscapers make good money knocking out a bunch of small postage stamp lawns.
I suspect that your first group of customers are priced to cheap, your equipment is not the most efficient for their sized properties, you spend too many days going there, or all of them.
That is not their fault but yours. Raise those prices.
I have customers that want everything done. Some a mix of things. Then those that only want mowing.
I value my mowing only customers because they pay well and help fill my schedule.
Without them my bottom line would be a lower.