Dear EmtUnderwood,
It is difficult to advise when the complete objective is not offered. All of the suggestions offered to date are valid. However, you might be better served by starting at the beginning, by creating colored maps, showing: [a] must-have indoor HT coverage, must-have outdoor coverage, and [c] like to have outdoor coverage.
You can also create similar colored maps showing what coverage you currently have, and listing all of the equipment and sites now providing that service. Add to this, a complete description as to how the current system does not meet your needs. Be sure to include a description as to how you currently maintain your fleet, to ensure it is still working at full performance.
From this data, any experienced communications engineer with good RF modeling software can offer solutions. It is possible you may need additional receiver sites to enhance HT talk-in, or diversity receive at your main repeater site. But a regular monthly program to remotely test the repeater input sensitivity, with a calibrated signal is essential for long-term success.