Undoubtedly you will need to let go of some of those great ideas you had at the beginning of the project. Ideally, the milestones have been prioritized such that the ideas to be left on the shelf are not core elements of the game. At the Alpha stage of development, it is time to reassess the remaining work to be done, give consideration to new ideas that have germinated over the course of the project, and incorporate them into the schedule if they are viable. This may help to motivate the team through to the end. It is especially important that you nurture the team through the final phases of development.
Final testing can be an especially difficult time.
The bugs seem to never end and some are seemingly impossible to fix. The programmer may have some anxiety as to the integrity of a piece of code. As the Producer, this is yet another storm to weather. Do so by facilitating in anyway possible. Consult with technical support, for example, to help solve technical problems.